John Pazmino 
 NYSkies Astronomy Inc
 2014 February 14 
    One of the very rarest of astronomy events favors New York City in 
owl hours of 2014 March 20 Thursday. Asteroid #163, Erigone, passes in 
front of star Regulus and obstructs its light from reaching us!! 
    Occultations like this are common from the immense number of 
asteroids and of stars in their path, about a half million of each. 
The covering of a bright star, specially one readily spotted by the 
public with bare eye, by an asteroid over a given location is, uh, 
excedingly rare. It is litterally a once-in-liftime show. 
    Unlike an eclipse or occultation with the Moon, you have no 
anticipation of the cutoff of Regulus. You can not in small scopes see 
Erigone. At the moment of totality Regulus suddenly blinks out as if 
its power switch was flipped to 'off'. After a few seconds it turns 
back on again. And that's it. 
    I customized this article for astronomers in the NYSkies 
territory, out to 100 kilometers from Times Square, plus all of Long 
Island. Readers beyond this region must obtain locality-adjusted 
information for their own districts. 
    This piece incorporates substantial material from International 
Occultation Timing association and its staff. Special thanks go to Ted 
Blank and Steve Preston for providing much of the information here and 
a review of a draft version of this article. 
    There is abundant litterature about this star reaching back to the 
earliest times of recorded astronomy some five and more thousand years 
ago. Regulus was always a cardinal star along the ecliptic, watched 
and monitored by virtually all cultures cognizant of the planetary 
motions. In about 2200 BC Regulus marked the summer solstice point. 
    I give here only a few considerations for it. One fascinating fact 
is that Regulus is not a sphere. It rotates rapidly to squish its 
photosphere into a oblate spheroid! Altho here to fore this shape is 
studied by interferometry, this occultation MAY reveal it from 
processing your observations. This is no promise but is COULD result 
that the recorded behavior of Regulus is best explained by a 
ellipsoidal, not circular, disc. 
    Some specifications of Regulus are given here. Please be aware 
that because these data came from diverse sources, certain items may 
be discordant against each other. 
    Proper name       Regulus; Cor Leonis; Al Kalb al Asad; Kabeleced 
    Bayer letter      alpha Leonis 
    Flamsteed number  32 Leonis 
    Yale Bright Star  HR 3982 
    Tycho             TYC 833-1381-1 
    Pos Pro Mot       PPM 127140 
    Henry Draper      HD 87901 
    Zodiacal          ZC 1487
    Fund'l Katalog 5  FK5 380 
    Smithsonian       SAO 98967 
    New Susp Var      NSV 04751 
    Hipparcos         HIP 49669 
    Bonner Durch'g    BD +12:2149 
    atlas charts
    Herald-Bobroff    chart C-49 
    Millennium Atlas  chart 731-732 (Vol II) 
    Sky Atlas 2000.0  chart 13 
    Uranometria 2000  chart 189 (Vol 1) 
    coordinates (J2000.0) 
    Right Ascension  10h 08m 22.3127s 
    Declination     +11d 58m 01.955s 
    Ecliptic long   160d 1.5m 
    Ecliptic lat     +0d 27.9m 
    Galactic long   226d 25.6m 
    Galactic lat    +48d 56.0m 
    distance & motion
    Distance         76.9 ly, 23.6 pc 
    Trig parallax     0.04240 arcsec 
    Prop motion RA   -0.25218 arcsec/yr 
    Prop motion DE   +0.00660 arcsec/yr 
    Radial velocity +10.2 km/s 
    Visual magnitude +1.41 
    Mean B magnitude +1.360 
    Mean V magnitude +1.399 
    Max V magnitude  +1.35 susp var 
    Min V magnitude  +1.47 susp var 
    Johnson B-V      -0.036 
    Abs magnitude    -0.52 
    Luminosity      123 Sun 
    Spectral class   B7 V 
    Temperature   10700 kelvin  
    Radius            4.1 Sun 
    Mass              3.8 Sun 
    Duplicity         Quadruple star
    Shape             oblate spheroid 
    New York City 
    Rise azimuth    +73d 42m 
    Culmination alt +61d 18m
    Set azimuth    +286d 18m 
    Diurnal arc      13h 32m
    The name is Greek, 'eh-RIH-go-nee'. Don't say 'EH-rih-gohn'. 
Erigone is a larger asteroid, some 70 kilometer diameter, but of 
uncertain shape. The data here come from various sources and seem to 
be about as good as any others to hand.
    DiscoverY year        1876 
    Asteroid number        163 
    Proper name              Erigone
    Linear diameter         72 km
    Category                 C-carboneceous
    Albedo                   0.04 
    Absolute magnitude H    +9.41 
    Magnitude slope G       -0.04
    Observation record
    Date of fit           2014 Jan 19
    Number of good obsns  1288
    Number of rejects       98
    Timespan of obsns     1903 Sep 23 - 2014 Jan 18
    Orbit elements
    Epoch of elements  2456736.255 TDT, 2014 Mar 20.255 
    Mean anomaly at epoch   46.28782507 deg
    Arg of perihelion      298.23787787 deg
    Long of asc node       160.17363738 deg
    Inclination              4.81452364 deg
    Eccentricity             0.19116015
    Semimajor axis           2.36690097 AU
    Perihelion dist          1.91444383 AU
    New York City
    Angular diameter         0.084 arcsec
    Distance from Earth      1.185 AU
    Visual magnitude       +12.4
    Duration of totality    14 sec, probable maximum 
    Projected path width   108 km 
    Totality hour & date    02:05 EDST Thu 20 Mar 2014 
    Uncertainty of hour      3.9 sec 
    Shadow speed WRT Earth   5.09 km/s 
    Regulus position        44 deg alt, 243 deg azm
    Moon aspect             87% sunlighted, 71d E of Regulus 
    Sun aspect               full night
Ground path  
    The ground track of the occultation in the vicinity of New York is 
given here. The path is about 100 kilometers wide, centered on the 
ground track. In the NYSkies territory the asteroid enters from 
southeast, passes right thru New York City, and leaves to northwest. 
    The favored locations within NYSkies are  Tappan Zee and Mid 
Hudson, Catskills, Taconics, southwest Connecticut, north New Jersey. 
most of Long Island (missing the east ends of the Forks), most of New 
York City (missing Staten Island), The west and south sectors of 
NYSkies are off of the west edge of the shadow oath. 
    Observing from beyond this zone is absolutely needed and can 
produce valuable information on the lateral limits of Erigone's size. 
Please stand watch for this occultation REGARDLESS of your location!! 
A negative observation is as worthy as a positive one. 
    There is an uncertainty of up to 4 seconds in time along the path 
and of several kilometers to either side of the path. This combines 
the unknown topography and shape of Erigone and displacement from its 
predicted motion. An other error source is the astrometry of Regulus. 
 Center line--------- UT hour-- Star---- Sun 
 W Long    Latitude   March 20  Alt Azim Alt 
 --------- ---------- --------- --- ---- ----
 72d27m43s +39d39m38s 06h05m47s 42d 247d -48d
 73 14 06  +40 30 03  06 06 09  42  246  -47 
 74 00 08  +41 20 41  06 06 30  42  245  -47
 74 45 53  +42 11 33  06 06 52  42  243  -46
 75 31 23  +43 02 41  06 07 13  42  242  -45
    Mind very well that the occultation occurs under Eastern Daylight 
Savings Time, FOUR hours behind Universal Time. For the City the star 
blinks out at 02:06 EDST and NOT 02:06 EST. 
    You may plot the center line on a topographic map to see what you 
may expect from your location. For other lat-lon within the range 
given here linear interpolation is adequate. 
    The closer you are to the edge of the path, 50 kilometers parallel 
to the center line, the shorter is totality and greater is the chance 
of a complete miss. 
Possible satellites 
    Erigone has no known moons. Since moons are already known around 
even smaller asteroids, it's possible that observers beyond the 
central path will see Regulus shut off ever so briefly due to an 
outlying moon. This is a stretch of hope, yet sometimes major new 
astronomy springs from accidental discovery. 
    This means that the zone of POSSIBLE blinking of Regulus is NOT 
just in the shadow path, but for about 700 kilometers adjacent to it 
on both sides. This zone within the US covers the eastern Great Lakes,  
Ohio Valley, Appalachia, Mid Atlantic, Chesapeake Bay, New England. 
    A satellite may be ahead or behind Erigone, in a zone again 700 
kilometers wide. With a nominal speed of the asteroid's shadow on the 
ground of 5 KPS, a satellite COULD touch Regulus as long as 150 
seconds before or after the asteroid itself does. Or, EEeek!, Erigone 
misses Regulus but a moon of it hits the star. You may want to stand 
watch a couple minutes early and keep it thru a couple minutes after 
the totality hour. 
    A shutoff of Regulus by a moon is very brief, less than a second. 
For this reason, the blink COULD come from a local terrestrial action, 
like by a bird or lofted rubbish. To confirm a blink by an Erigone 
satellite we need at least TWO consistent observed events along the 
same axial line. 
    I stress there are NO predictions for events by satellites of 
Erigone. It could easily turn out that NO moons are detected from this 
Possible companions 
    In this century we found so far three companions of Regulus. One 
is a close-in comes making a binary star with Regulus. The other two 
are a second binary star in a distant orbit around Regulus. This star 
is the here to fore assumed line-of-sight companion that is commonly 
mentioned in observing guides. 
    For all feasible observing methods for home astronomers the 
occultation will not produce any evidence of the inner component. The 
outer pair casts its shadow well off of Earth. Perhaps an observatory 
with high-speed, high-resolution, photometry may find the close 
companion against Regulus. This is very iffy. 
Finding Regulus
    For newcomers to the sky it can be difficult to confidently point 
to a star and correctly identify it. I'm not joking. IF you watch the 
wrong star, thru ignorance or mistake, you will LOSE THIS OCCULTATION 
with essentially no further opportunity for a second chance for the 
rest of your life!! 
    Get familiar with Regulus NOW, long before the occultation! It's 
in high sky in east and southeast at nightfall in March. Once found, 
you can follow it thru the night to the occultation. 
    Most starID litterature tells you to find the 'Sickle' asterism 
forming the head of the Leo constellation, of which Regulus is the 
heart. In a sky with strong haze, moonlight, luminous graffiti the 
Sickle is obscured. Its other stars are weaker than Regulus. 
    Exercise your planetarium software. Start at a known group like 
the Big Dipper or Orion. Walk from them toward Regulus, making sure 
you match wayside stars with the software display. You may also use a 
mechanical device, like a planisphere, but be wary of its distorted 
map projection. 
    For this event, Regulus is on the line from Jupiter thru the 
Beehive cluster as as far beyond. It is also quite half between 
Jupiter and Mars. ti is roughly an equilateral triangle with Alphard 
and Caput Hydrae. It's a full Dipper's length south of the Big Dipper 
at the south end of the Sickle asterism. 
    For aiming a camera at Regulus, the star is too dim to show up in 
the finder screen. Carefully note above which landmark in the 
landscape Regulus stands and aim with that feature near the bottom of 
the screen. 
    Once getting Regulus in the camera field you may zoom in or change 
to a tele lens. Keep the field of view at least one degrees wide. This 
allows Regulus to drift diurnnlly for a few minutes before and after 
the occultation. At the time of the event Regulus is drifting from 
upper left to lower right in the sky. 
    As far as I know digital cameras don't have changeable finders and 
screens, like for chemocameras. With the older cameras astronomers 
could aim and focus their celestial targets on a bright clear scene. 
    Please check your camera operations! Some cameras notch to some 
close focal distance if there is no obvious target to fix on! You 
could be foiled by Regulus being so strongly defocused that it diluted 
out of sight. You may have to manually set the focus to infinity. 
    Bear in mind that even if the sky is hazy with few other stars in 
sight, you will see the occultation. As long as Regulus presents a 
definite firm image, you'll see it turn off and then turn on as well 
as if it was shining in a pristine sky. 
New York sky
    During the occultation Regulus is half up in southwest. Orion is 
gone below the west. The east half of the Winter Hexagon, or Super 
Bowl Football, arcs across the west. Virgo with Mars is culminating. 
    From Mars the zodiac slants to the southeast thru Moon, Saturn, 
and Caput Scorpii. Vega is about 1/4 up in northeast. The Big Dipper 
is in high north. 
 .  To be sure your viewing spot has a clear sightline to Regulus, 
simulate the sky with planetarium software and measurements of 
potential obstructions at the site. Don't be killed by a surprise 
blockage of view because you didn't do your homework. If nothing else 
works, physicly look at Regulus at 02h EDST from your spot on days 
before the occultation. 
    The Moon is a waning gibbous that may wash out fainter stars but 
will pose no threat to Regulus. A haze or thin cloud could scatter 
excessive moonlight and dull Regulus. 
    The bright Moon will oblitterate two weak meteor showers active 
during the occultation. These are the beta Leonids and zeta Leonids. 
They have only a couple meteors per hour under ideal conditions. 
    The occultation is an extra point of data for the GLOBE at Night 
exercise. Orion, the target for GLOBE at Night, already set. 
    You may assess the sky by stars in Leo. Regulus is magnitude 1. 
Denebola and Algieba are magnitude 2. Chort and Zosma are magnitude 3. 
The rest of the Sickle asterism is magnitude 4. Stars in Leo Minor and 
Sextans are magnitude 5. Include a note about the extent of lunar 
interference for this measurement. 
    Please do the GLOBE at Night inspection of  Regulus WHILE IT IS IN 
FULL SHINE!!. Saying the sky was too bright to see Regulus when in 
fact the asteroid was sitting on top of it will earn you the laughter 
of the century. 
    Because of the Moon you probably will not get much deep sky 
observing. Nor will you see any but the brightest of aurorae, if any 
occur. If you're staying under the sky for a while, shift to observing 
double stars, Mars, Saturn, and learning star-ID. 
    Here's a timetable for the night of 2014 March 19-20, Wednesday-
Thursday, for this show. All hours are Eastern Daylight Savings Time. 
        EDST  | event               | remarks
        19:07 | Sun sets            | azimuth 91 deg
        19:34 | civil twilight      | end of daytime work
        20:06 | nautical twilight   | start of full night in NYC
        22:24 | Moon rises          | azimuth 109 dwg
        23:14 | Regulus on meridian | altitude 61 deg 
        00:00 | midnight            | March 19 --> March 20 
        02:06 | Erigone-Regulus occ | alt 44 deg, azm 243 deg 
        03:46 | Moon on meridian    | altitude 34 deg
        05:58 | Regulus sets        | azimuth 286 deg
        06:00 | nautical twilight   | end of full night in NYC
        06:32 | civil twilight      | start of daytime work
        06:59 | Sun rises           | azimuth 271 deg
Date and hour 
    It's astounding how even seasoned astronomers can louse up the 
date of an event occurring in the midnight to dawn span. You must be 
specially careful for the crossover at midnight into the next calendar 
date. Missing that crossover puts you a full day out of step. 
    Already I'm seeing some sloppy advice to set up in the late night 
of March TWENTIETH. This level of mistake slides you a whole day too 
late. You're under Regulus at 02h EDST on the TWENTY-FIRST. 
    You do supper and a nap after sunset of March 19th. See the 
occultation a few hours later on March 20th. Greet the rising Sun 
later on the 20th.  
    The occultation occurs after the annual idiotic shift into Eastern 
Daylight Savings Time! The crossover is on Sunday 9 March. EST is FIVE 
hours behind UT; EDST, FOUR. 
    If you set up for 2AM EST, because you compiled plans before EDST 
starts, you miss the occultation by a full hour. You were out there at 
3AM EDST. Regulus for the rest of your life shines on and on. 
Viewing location 
    View this occultation from any convenient location. Regulus is in 
high sky, clearing most city skyline. You may use your normal 
stargazing site if you want. It isn't necessary because Regulus is 
accessible from all parts of the City. It is crucial that observers be 
dispersed over the whole width of the shadow path and even beyond it. 
    While it is almost irresistible to seek the center line of the 
path for the longest totality, like for a solar eclipse, this is 
really NOT what is wanted in this situation. The profile of Erigone 
could be such that the longest totality is OFF of the center line! One 
purpose of viewing this occultation is to map out the shape and size 
of the asteroid by collecting timings from its whole diameter. 
    This is why the best location could very well be your own home or 
a nearby spot, NOT a remote stargazing site. Apart from simplifying 
your observing plans, skipping most of the travel hassles, you enhance 
the value of your observation by getting a measure of the asteroid 
along a new and unique path. 
    Mind well that the event occurs at about 02h EDST, when many 
plausible sites are closed or off limits. 
    If you plan to travel to a site, be VERY AWARE of rail and road 
disruptions in owl hours. These hours are favored for massive work on 
substantial segments of road and rail thruout the NYSkies region. 
    Several astronomy clubs are arranging for in-house observing of 
the occultation for their members. They may use a site that's normally 
closed to the public but is open by arrangement with the club. 
    Most will be happy to accommodate you, as a serious observer. If 
you obtain invite to join observers, you take part as an observer! Do 
NOT behave like at a public stargazing meet. Keep quiet, leave other 
astronomers alone, maintain polite deportment. 
    NYC Events does not list internal events. You should inquire via 
the contact for the club's listed public events. 
Public viewing 
    There probably will be few public viewing for this event. The owl 
hour and instantaneous action of Regulus work against such a viewing. 
Assume you will view this occultation on your own, whether by yourself 
or with other convenient astronomers. 
    In the NYSkies region there are many observatories, typicly at 
colleges and universities. Some may be cranked up to record the 
occultation. It is not feasible for a public audience to watch Regulus 
thru the telescope due to the limited facilities for such groups and 
the excedingly brief totality. 
    It COULD be possible that an observatory can pipe images of the 
star, maybe with the asteroid, to a lecture room. There the images are 
showed on screen with live narration by observatory crew. As at issue 
date of this article I have no news of any such show. Do ask at the 
local observatory for its plans. 
Geographic position 
    As an astronomer you should already know the geographic position 
of your observing site. Nowawyears this is taken from GPS receivers 
and recorded somewhere in your observing kit. Besides a dedicated GPS 
receiver, your smartpphone may allow a position readout from its 
onboard GPS circuit. 
    You may still use the older technique of scaling off of USGS 
toposheets, county survey maps, military cadasters, and the li. Other 
sources for precise coordinates are the Internet mapping webs or GIS 
    Mark your location within the displayed landscape, zoom in to get 
a better fix. Do this for each plausible location you are considering 
for viewing this occultation. 
    You need the coordinates to the 1/4 arcsecond in each axis because 
the asteroid's relief is in the order of a tens of meters. 1/4 
arcsecond is, uh, 7 to 8 meters on the ground. 
    You need a stably mounted telescope. Just about any scope is good, 
so long as it has a sturdy steady stand, produces a solid clean image 
of Rwgulus, follows the star easily. This may be by motor drive or by 
smooth hand controls. 
    There is no need or desire to get hold of a large or powerful 
telescope. Regulus is a bright star and Erigone can't be seen in any 
scope you're likely to find to hand. You're watching for the total cut 
off of Regulus as Erigone crosses over it. There is no detail or 
structure to see, like for a lunar occultation or eclipse. 
    Magnify Regulus as high as possible while still keeping it a solid 
image. If there is little moonlight, luminous graffiti, haze, you may 
spot the remote companion star of Regulus. It's 8th magnitude, 3 
arcminutes to the northwest. 
    Your hands, eyes, mind, body must be relaxed and free of stress. 
Sit down, on a chair or stool or sturdy box. at the telescope. Turn 
the eyepiece at a comfortable angle and height toward the eye. 
    Keep stray lights off of your face with shields of cardboard or 
other opaque stiff material. A hooded jacket is helpful but the hood 
could hinder you if you must handle equipment away from the eyepiece 
like a audio recorder or computer. 
    Remove potential distractions like phone calls and interference 
from pets. Let the rest of your household know you need calm and quiet 
with no loud noise or annoying questions.. 
    Eat well an hour or so before setting up for the occultation. Get 
good sleep, at least a nap. Stay off of stimulants, even coffee. If 
you normally use medical eyedrops, apply them before the observation. 
Powerful trick
    THere's a trick sometimes used for lunar occultations of bright 
stars. DELIBERATELY defocus the telescope to make Regulus a small 
disc. Its face will be irregularly lighted due to atmospheric 
    This disc may be more confidently watched than a sharp point. When 
Erigone touches it, the entire disc blinks out at once, with no fading 
or dimming. After totality the disc of Regulus suddenly comes back 
into view. This trick helps to distinguish momentary dimming from 
twinkling from the real cut off of starlight by the asteroid. 
    There is the prospect of seeing with the defocused disc the 
kinetics of Erigone moving across Regulus. The disc may not blink out 
all at once but very rapidly, as if a door or lid was slammed over it. 
This is speculative, yes, but it's something to be mindful of. 
    Most astronomers can cope with defective vision for telescopy. Low 
vision folk who miss the fainter stars in the sky by bare eye usually 
achieve full resolution and amplification with the telescope. 
    Two main factors can impede an observer for the occultation are 
floaters and dead spots. Floaters are bits of eyeball lining that 
somehow broke loose and are trapped in the liquid filling of the 
eyeball. They show up as 'amoebae' drifting thru the visual field. In 
daylight they are mostly innocent nuisances but at night they can be a 
disaster for this occultation. 
    By swooshing the eye left-right the floaters are agitated and can 
scoot past Regulus in the eyepiece field quickly enough to avoid 
masking the star's shutoff. Trying to hold the eye still lets the 
floaters settle at the bottom of the eyeball, seen as drifting to the 
top in the visual field. This is a tough tactic since you WILL jiggle 
the eye as a breeze hits it, a tear starts to drip, other distraction. 
    The other factor is a dead spot on the retina. In daylight you 
probably never notice it because the eye-mind vision mechanism 'fills 
in' the missing detail and the eye is in constant movement to take in 
the landscape. At the telescope the effect is to blink out stars in a 
certain area of the eyepiece field. Jiggling the eye restores the 
stars but the dead zone remains fixed in the field. Be wisely of this 
situation in your vision, perhaps from prior observing experience. Put 
Regulus in a quarter of the field away from possible interference from 
the dead spot. 
    One other defect that should be considered is astigmatism. Regulus 
will focus to a small, but finite, dot. A bit of defocus renders it 
into a short line. This image when hit by Erigone will snap out of 
sight, then snap back into view, all at once 
    This occultation is remarkably resilient against adverse weather! 
As long as there are no thick or varying clouds, you'll see Regulus. 
Even haze or thin cloud is no barrier.
    Clouds scudding along, intermittently blocking view of Regulus, 
are a severe hazard, as are clouds of variable density. The star 
shines thru the thinner parts but is hidden behind the thicker parts. 
    One clue to catching the correct shutoff is that Regulus will turn 
off instantly with no gradation of brightness. Same for the return to 
normal brilliance many seconds later. Covering by mist, cloud, haze is 
always gradual, with obvious dimming and swelling of light. 
    The air in owl hours of late March can be chilly. Wear a winter 
coat. Have gloves and hat to hand in case the air gets too cold. 
    Prepare for moisture, specially if the night is within a spell of 
rain. Dew can also form on optics and electronics if there's a steep 
temperature drop from day to night. Have a dew zapper or small hair 
drier handy 
    If you use ANY electric or electronic device, you WILL be 
threatened by malfunction at the critical moment! March chill and 
moisture can upend the works unexpectedly. Be ready and willing to 
fall back to a simpler manual observing method. 
Did Regulus blink? 
    For readers with only a simple telescope there is creditable work 
you can do. Diligently watch Regulus over a few minutes spanning the 
occultation hour. Note carefully whether Regulus ever did blink out, 
even if briefly, or it shined continuously with no interruption. 
    This observation bounds the maximum lateral dimension of the 
asteroid. You may add a qualitative description of the duration of 
    In theory, and this is touted by some authors, you  can watch by 
bare eye. This is a VERY risky attempt. There will always be continual 
and often random annoyances around you to momentarily divert your 
attention. You will also be interdicted by the vision factors such as 
those discussed in 'Eyesight'. 
    A severe impediment to a confident observation by bare eye is 
twinkling. In strong wind Regulus may scintillate to send u false 
alarms. You can easily miss the true occultation and record a long 
    This event is NOT like watching an aurora or meteor shower. You 
must keep close attention on Regulus with no interruption of any kind 
This discipline is almost impossible to enforce by merely standing 
outside and looking up. Sitting can improve your work but not enough 
for confident observation. Use at the very worse a tabletop telescope 
on a stable stand.   
    This is a fetching example of a celestial event seemingly beyond  
newer home astronomers to appreciate. It turns out to be among the 
very easiest to experience, and make useful worthy observations. 
Counting cigarets 
    An elaboration of the 'did it blink?' effort is to start counting 
'cigarets' instantly Regulus shuts off. The time to say 'one cigaret' 
swiftly but distinctly is quite one full second. The four syllables 
are each quite 1/4 second. To maintain au even cadence, say 'sevv' for 
'seven'. Restart the count for each round of ten seconds. Tally the 
rounds of ten on a notepad. 
    We believe the shutoff will last a dozen or so seconds at the 
most. Please be prepared in case we got the axial dimension of Erigone 
wrong. Catch when Regulus appears again. Note the syllable just 
COMPLETED when the star came back and the associated number word. 
    You'll be startled when Regulus turns off and suffer a split-
second delay in beginning the count. You will again be surprised when 
Regulus pops back into sight. The delays at both ends more or less 
cancel out. 
    This same reasoning applies to other timing methods where you must 
manually act at both ends of totality. like pressing a stopwatch 
button or tapping a timing software icon. 
    The number word STARTS the second. The second for that word ends 
when the syllable '-ret' is sounded. The madeup timing below tells you 
that totality lasted about 3-3/4 seconds 
  'one-ci-ga-ret,  two-ci-ga-ret,  three-ci-ga-ret, four-ci-ga- --' 
  |---second #1---|---second #2---|---second #3---|-incomplete sec #4 
The very last syllable 'ret' was sounded after Regulus reappeared. 
Eye and hand 
    The next level is to time the duration of the shutoff with a 
stopwatchor, The length of occultation is likely to be only a few 
seconds. Yoy must be ready and quick to start the watch soonest 
Regulus turns off and to stop it sonnest Regulus turns back on. 
    Most cellphones have a stopwatch function. The display is either 
the duration, or two absolute times. For the latter case only the 
difference of the times, the duration, is valid. Phone companies are 
seeming lazy about synching their absolute times to the global timing 
    The record gives the axial dimension of Erigone as it flies over 
your location. Altho you have no absolute start and end hour, the 
length of the 'off' phase can correlate and check other observations 
along the same axis. 
    You may run an audio recorder while you speak the start and end of 
the covering, along with an overlay of shortwave radio time signals. 
By playing the recording you can measure the time of events against 
the time signals. Use a crisp words, like 'off' and 'on', not, as 
example, 'saw' and 'see'. The latter have a prolonged initial sound 
that last several tenths of a second. 
Timing software
    An other method is to play a computer timing program that collects 
times by pressing a button or icon. The advantage is that the timing 
is recorded by the program to be retrieved later. The simpler ones 
mimic a stopwatch, to the level of displaying a dial on the screen. 
    The fancier softwares also capture the absolute time of the event, 
not just a relative one, by riding an external time service. 
    Here is a warning about the hour shown by a cellphone. Altho it 
is issued by a precise circuit in the device it could be out of synch 
against global time services. 
    Be sure your software actually rides the world atomic clock 
services and not just that in the device. The discrepancy can be a 
couple seconds! The phone company isn't all that diligent about 
keeping in synch with the global time network. It may synch once a day 
and let its time signals wander else when. 
    Some softwares allow you to send via email the recorded timings 
directly to IOTA or other occultation center, In such models you first 
fill in some personalia and specs of the event. 
    As at this article's issue date software suitable for this event 
play on iPhone and Android devices. 
    Tou may videograph the event and use the frame count as the timing 
mechanism. Timing only the duration can be done with a stand-alone 
video device. One such is a digital camera that stamps a count on each 
frame. Setting this device on a tripod aimed at Regulus with a tele or 
zoom lens should give frames that show the star, then many with no 
star, and then the rest with the star again. The duration comes from 
the sequence stamps on the frames with no Regulus in them. 
    The frame rate gives the duration of the blinkout. If, made up, 
fifty frames capture Regulus in the shut off phase and the camera is 
shooting 24 frames per second, the duration is 
    (duration) = (number of frames) / (frame rate) 
               = (50 frames) / (24 frames/second) 
               = (2.083 seconds) 
              -> 2.1 seconds 
    You can imprint an absolute time with the video by first shooting 
Regulus and then WHILE LEAVING THE CAMERA RUNNING aim at a display of 
absolute time on your computer. Let this display impress for a couple 
seconds, THEN turn off the camera. The frame count from a time mark at 
the end of the video back to one of the contact events gives the hour 
of each event. The maths are like that shown above. 
    The time display may be out of focus because you were shooting at 
infinity on Regulus and then aiming at a target close to you. As long 
as the digits in the display are legible, if blurred, you got the 
absolute time. You may place the time display a dozen or more meters 
away to lessen the out-of-focus problem. 
    Improve the chances of getting Regulus to impress an image by 
setting the 'film' speed, the ISO or ASA rating, to a high level. The 
picture will be filled with static, like the 'snow' on analog 
televisions. Regulus will be the only enduring image, covering many 
pixels. When it is hidden by Erigone, ALL of its pixels go dark at 
once. ALL come back on when Erigone leaves the star. That's the 
fundamental observation, regardless of how awful the image looks. 
Computer caution 
    You may be tempted to simulate this event with a planetarium 
program. If Erigone is already in the database of orbits, it is for 
sure totally ediurnate. Asteroid orbits go out of date after a few 
years. Running simulations with ediurnate data yields wrong results. 
    You MUST get current orbit elements! These come from the Minor 
Planet Center or JPL Small Solar System Body database. The elements 
presented under 'Erigone' are valid as at late January 2014 and are 
probably as good as you'll get then after. 
    Carefully key in the numbers into your planetarium. How you do 
this is peculiar to each planetarium software. Study and exercise its 
    You will NOT see Regulus blink out in the simulation. All 
planetaria I ever saw treat asteroids as dead points. The best you can 
expect is to watch the asteroid's dot touch and merge into Regulus, 
then glide away on the other side. The star shines during totality. 
News and information
    As astronomers gear up for the event there will be a chatter 
thruout Internet. One good starting place for general news, including 
latest predictions, is International Occultation Timing Association, 
IOTA, at
To report your observations, stop at
    This excedingly rare instance of an asteroid covering a bright 
bare-eye star for us in the NYSkies land should not be passed up! What 
may at first seem an impossible observing event is actually among the 
very easiest of all celestial activity to appreciate with simple 
instruments. And it requires no special place to view from. 
    There likely will be no future occasion for the City within this 
generation for so bright a star to blink out of sight because a city-
size rock blocks its light. As long as there are no severe clouds, we 
have a good chance to realize this experience.  
    Weather in March is usually mild, altho a lingering winter chill 
can prevail. But that's easily handled with ordinary outer garments 
and comforts. Only thick or roving clouds, and rain or a late snow, 
will derail your effort.