22 Kalliope Occults a 9 mag star

This note is essentially written for those amateur astronomers who do not have prior experience in observing such events.

On the night of 24th of December 2016 asteroid 22 Kalliope will occult 9th mag star. The star is bright enough to be spotted using a telescope with 100 mm (4inch) primary mirror. The occultation path is about 160 k.m. wide.

Kalliope has one known natural satellite, Linus with diameter of about 28 km. Two major cities close to the path of Linus are Udaipur and Ujjain.

Indian astronomers are well placed to observe this event with approximate track joining Jamnagar in west and Nallore in east.

22kalliopepath

For interactive map Google map of the shadow path by Derek Breit, for the map of path for: 22 Kalliope click here and for   Linus click here.

I have put some identification maps in pdf format. You may right click and save the maps for printing.
These are as follows:
22kalliopea This file shows large field of view – Auriga, Gemini and part of Taurus

Next two maps are with field of view of 6.3 deg. These are two sets of maps with drawn RA and Dec lines and without any lines.  One set has RA increasing to left and the other set is exactly reverse.
22kalliopeb  (has three maps) and   22kalliopec  (has one map)

On this page:

  1. Brief summary of  the event 
  2. How to observe/what to record
  3. Stars maps to locate the star to be occulted
  4. Links to external pages/sites
  5. List of some stations inside or near the shadow path

1) Brief summary of the event in (essentially in Indian context)
A 9th mag star TYC 2430-01124-1 will be occulted by asteroid 22 Kalliope. Some of the major Indian towns and cities inside the path or close to the path are listed in item (5) below.  At the time of occultation, altitude of the star would be about 50 deg. in western part and about 45 deg close to eastern part of India (in western sky).  The event will take place around 03:40 IST.

Designations of the Star: TYC 2430-01124-1 =  SAO 59102 = HD 45249 = BD +34 1351
Mag V 8.94,  RA 06h 27m 54.6s;  Dec +33º 54′ 58.8″
Expected maximum duration 13.5 seconds, expected drop 1.3 mag

The event takes place at 3h 26m IST  (check this link for finding exact time for your site)

Diameter of 22 Kalliope’s is 167 k.m.  At the time of occultation it’s mag. will be 10.1

~~**~~

2) How to observe/what to record

We must keep in mind that it is the duration of the occultation that we need to record. It is really not necessary for one to look for the asteroid itself.  And, therefore, the first step in preparation is to clearly identify the star to be occulted and the field around it. This should be done well before the event.

(From now on the star would been the star to be occulted i.e. TYC 2430-01124-1)

Identifying the Star: As said before the Star is well placed in the sky and is in very identifiable region between Gemini and Auriga. The star is just about 13° east of Castor (α Gem) or 6.75° west of  θ Aur. Most interestingly, halfway between these two we have 3.4 mag star θ Gem which has nearly at the same declination (+33° 56′) as that of the Star (see above) and is less than 5° east of it.

Thus, first you can quickly hop from α Gem or θ Aur to θ Gem and from there a) to the Star, or b) if you have a telescope on well aligned equatorial mount then from θ Gem move the scope to east by about 5°.

What will I see: To begin with you must identify the Star and track it. The asteroid at the time of the occulation will be about 10 mag and one is quite likely to see it in a 150 mm (6inch scope). One would see the asteroid moving closer to the Star. At some point very close to the event they would appear to merge into each other. And then there would be a drop in the brightness as the asteroid comes between us and the star. Depending upon where one is located the duration would  very.  Those close to the central path are expected to see the ‘return’ in about 13 seconds.

If one has a smaller telescope, say with 100mm (4 inch) primary, then one might miss the asteroid. There the event will be even more dramatic. You are looking at the star and then it simply vanishes from the field to reappears again in a few seconds.

{Here we are talking about limit of the faintest star that is easily observable,  theoretical limit is nearly two magnitudes fainter}

What do I record (so that my observations would be useful for the astronomical community) : Two parameters would be of utmost importance – 1. exact location (latitude, longitude) and 2. the duration of the event – that is the difference between the start and end time of the occulation. Without this your observations would be of little value.  The altitude of the event is also important but one can easily find that if the exact location is known.

If you have a good smart phone and a telescope that can help you to observe the event then you are there to make your own contribution to the science of asteroids.

We presume here that every one who is likely to take part in this observing exercise has a mobile phone with stopwatch app on it.

Just in case you have not installed one of those GPS apps on your phone then please do so. 

What if your phone does not allow you to install a GPS app?  Then at least correctly record the place from where you took the observations so that the lat long and alt of the place can be found from the interactive map (check out Derek Breit’s link below).

After that all you have to do is to point the telescope to the Star.  It is always better to have the star SURELY identified about 30 min prior to the event and keep it fixed on it.

TRAP – I remember, once one enthusiastic amateur, after identifying the star well ahead of the event, moved the telescope to a near by M object and he then could not get back to the star in time to observe the event.

TIP – remember you are on a very serious mission and likely to make a contribution to the science of asteroids. So take this with complete seriousness. If possible check the site at least one night before. Avoid every thing that might distract you.

TRAP – if you are on the eastern side of a highway then it might happen that you might face headlights of vehicle plying on the highway. Avoid that.

TRICK – if such a situation arises – have your friend ‘occult’ the light by stand between that and the scope.

What more : if you can record the exact time of the start and end of the event it is even better.

Some amateurs have recorded what is called the star trails using a camera.  In the image you see trails of different stars but trail of one star is broken in between (as it was occulted by the asteroid).  As a picture it looks good but it is a pain to extract useful information from it. It is far better to time the event.

~~**~~

3) Stars maps to locate the star to be occulted

22kalliope01

This is a wide field to give you idea of the region of sky we are interested in

22kalliope2degfov

Use this map to hop from theta Gem to the Star marked by arrow

22kalliope04

The star marked by arrow and field around it

22kalliope05

Same as above with star magnitudes given ([1014] means 10.14 mag)

~~**~~

4) Links to external pages/sites

For the details of the event by Steve Preston click here.

This link has detailed Maps for: Europe , India , Linus , Linus[Europe] , Linus[India]
Detailed Info (updated 2016 Nov 13, 22:12 UT)
Finder Charts (courtesy of Guide): Wide Field , 15 degree view , 5 degree view , 2 degree view , 30′ view

For interactive map Google map of the shadow path by Derek Breit

For the map of path for: 22 Kalliope click here and for   Linus click here.

~~**~~

5) Some of the major Indian cities or towns inside the shadow path are :
{Place km (North or South)}
Ahemednagar (16 N), Dombiwali (80 S), Bhavnagar (86 N), Dwarka (68 S), Igatpuri (6 S), Jamnagar (20 N), Junagadh (40 S), Kalburagi (4 N), Karjat (14 S), Latur (72 N), Nashik (35 N), Nellore (46 S), Porbandar (81 S), Rajkot (50 N), Solarpur (35 S), Surat (76 N), Vapi (13 N)
Barshi on the central line
Mumbai (south) and Hyderabad (north) are just going to miss the event whereas, Pune (south) is in one sigma error limit.

~~**~~

This event will certainly generate lot of interest in observing occultations.  If you would like observe more occultation why not fill this google form.  We will keep you updated.

Please feel free to give your comments views etc.

Or email  me at paranjpye.arvind@gmail.com

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About skytonight

I am the present Director of Nehru Planetarium of Nehru Centre Mumbai, India I like to talk about astronomy and sky observations to general public.
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