IL Aqr/GJ 876 Campaign

October 1, 2004: IL Aqr, known as GJ 876 in the exoplanet transit community, has two planets orbiting it. On October 21, 2004, the AAVSO will be conducting a ten-hour observing campaign to detect the largest of these planets, GJ 876b.

Last updated: Wed Oct 27 13:36:50 EDT 2004

The main observing campaign is over. But we still need high-precision nightly observations through the end of the year.

Possible transit?

Day 1 (so far)

Day 2 (so far)

Day 3 (so far)

Campaign Details

Intensive time series observation of IL Aqr/GJ 876 on October 21 is needed to detect a possible planetary transit. CCD observations unfiltered and in V are requested. The transit depth may be as much as 0.1 magnitude, but high precision is needed to look for possible anomalous behavior during the ingress and egress. Please practice on this field ahead of time and submit your observations to the AAVSO.

Observing window:

Transit Prediction:
October 21 23:22 UT - 03:27 UT (Oct. 22)
w/1 sigma uncertainty:
October 21 18:22 UT - 08:27 UT (Oct. 22)
w/3 sigma uncertainty:
October 20 11:22 UT - 15:27 UT (Oct. 23)

il aqr is the red one

VRI image of IL Aqr/GJ 876 (the bright red one). Northeast is topleft. Image from Paddy McGee, of the University of Adelaide (used with permission).


E-mail aaronp @ to be added to this list. We need observers for the entire observing window, October 20 11:22 UT - October 23 15:27 UT and we need multiple observers per night.

Who Where When (weather permitting)
Roland Santallo Tahiti Oct. 21 05:00 UT - 10:00 UT
Oct. 22 05:00 UT - 10:00 UT
Oct. 23 05:00 UT - 10:00 UT
Pam Kilmartin St. John Observatory, New Zealand Oct. 21 - 08:30 UT - 16:30 UT
Oct. 22 - 08:30 UT - 16:30 UT
Oct. 23 - 08:30 UT - 16:30 UT
David Higgins (HDJ) Canberra, Australia 10/21 - 09:30UT to 15:00UT
10/22 - 09:30UT to 15:00UT
10/23 - 09:30UT to 15:00UT
Peter Nelson (NLX) Ellinbank, Australia 10/21 - 09:30UT to 15:00UT
10/22 - 09:30UT to 15:00UT
10/23 - 09:30UT to 15:00UT
Tom Richards (RIX) Woodridge Observatory, Melbourne, Australia Oct 21 09:30-15:30
Oct 22 09:30-15:30
Oct 23 09:30-15:30
Bernard Heathcote (HBD) Melbourne, Australia Oct. 21 09:30 -16:30 UT
Oct. 22 09:30 -16:30 UT
Oct. 23 09:30 -16:30 UT
Chris Stockdale Australia Oct. 21 09:30 - 13:30UT
Zsolt Kereszty (KZX) Hungary Oct 20 19:00 UT - 23:00 UT
Oct 21 19:00 UT - 23:00 UT
Jean-Luc Laurent (LJJ) Le Val Saint Germain - France Oct 20 19:00 UT - 22:00 UT
Oct 21 19:00 UT - 23:00 UT
Oct 22 19:00 UT - 22:00 UT
de Ponthiere Pierre DPP Belgium Oct 21 18:00 UT - 23:00 UT
Oct 22 18:00 UT - 23:00 UT
Oct 23 18:00 UT - 23:00 UT
Paul Shankland U.S. Naval Observatory, Washington, D.C. Oct. 21 - all evening
Oct. 22 - all evening
Oct. 23 - all evening
Charles Knapp (KCH) Renick, WV Oct 22
Oct 23
Shawn Dvorak (DKS) Clermont, FL Oct. 21 23:45 UT - 05:00 UT
Oct. 22 23:45 UT - 05:00 UT
Oct. 23 23:45 UT - 05:00 UT
Mike Fleenor (FMH) Knoxville, TN All 3 nights
James Case (CJS) Hound Hill Observatory, Kansas City MO
Michael Koppelman (KMP) Golden Valley, MN Oct 21 01:00 UT - 05:00 UT
Oct 22 01:00 UT - 05:00 UT
Oct 23 01:00 UT - 05:00 UT
Don Wells (WDZ) and Bill Dillon (DIL) George Observatory, Needvill, TX. Oct 21, 01:00 UT - 05:00 UT
Robert Koff (KRV) Bennet, CO Oct. 21 - 02:00 UT - 06:00 UT
Oct. 22 - 02:00 UT - 06:00 UT
Oct. 23 - 02:00 UT - 06:00 UT
Robert James (JM) Las Cruces, New Mexico Oct. 21 01:30UT - 07:30UT
Oct. 22 01:30UT - 07:30UT
Oct. 23 01:30UT - 07:30UT
Aaron Price (PAH) New Mexico Skies Robotic Observatory (UT +6) 10/21 - 01:00UT to 11:00UT
10/22 - 01:30UT to 11:00UT
10/23 - 01:30UT to 11:00UT
Jon Holtzman NMSU Apache Point 1m Robotic Telescope 10/21 - 01:00UT to 11:00UT
10/22 - 01:30UT to 11:00UT
10/23 - 01:30UT to 11:00UT
Rick Huziak (HUZ) Saskatoon, SK, Canada Oct 21 03:00 UT - 09:00 UT
Oct 22 03:00 UT - 09:00 UT
Bruce Gary (GBL) Hereford, AZ Oct 21, 01:50 - 07:50 UT
Oct 22, 01:50 - 07:50 UT
Ron Bissinger Pleasanton, CA Oct. 21 - 03:30UT to 13:30UT
Oct. 22 - 03:30UT to 13:30UT
Oct. 23 - 03:30UT to 13:30UT


(from CCD Views #326 - Oct 7, 2004)

 The AAVSO has teamed up with to coordinate an observing 
campaign for IL Aqr, a.k.a GJ 867 in the transit search community. Dr. Greg 
Laughlin, University of California at Santa Cruz, is looking for observations 
during an upcoming transit opportunity. 

IL Aqr is located at R.A.: 22:53:17.03  -14:15:52.5
 The GJ 876 system contains two planets orbiting a nearby M-dwarf star.  The 
planets are in an orbital resonance which leads to significant precession of their 
orbits. The causes the transits to be somewhat unpredictable and by observing 
the transits we can learn more about the orbital dynamics of the system.

 The purpose of the campaign is to detect transits of planet "b" if they are 
occuring, or to convincingly rule them out. Below are the transit windows:

=== Observations 

Transit Prediction:
         October 21 23:22 UT - October 22 03:27 UT 
w/3 sigma uncertainty:
         October 20 11:22 UT - October 23 15:27 UT

 ** Observations are needed during the entire 3 sigma window!! **

 In addition, IL Aqr is a variable star that has not been well monitored. It has a 
tiny GCVS range of V=10.15-10.19, however that is just enough to interfere with 
transit detection. We need observations of IL Aqr to begin now so we can set a 
baseline of activity. Please begin observing IL Aqr at least once per night in B 
and V with as high precision as possible. Use the 119 comp star on the chart 
(B=12.956 +/- 0.033) and set your exposure for a good SNR. If possible, get a 
few time series runs in of at least four hours. Submit your data as soon as you 
can so we can evaluate IL Aqr's typical activity (so as not to confuse it with any 
transit activity). 

 An e-scale chart has been created with 3 comparison stars from ASAS-3. It can 
be downloaded at: [obsolete link; 
create charts using VSP at ]

 The predicted transit depth *could* be relatively large, up to 0.1 magnitude. 
However detection of a transit is not assured, much less its amplitude! 

 However, there is a catch. IL Aqr is a very red star so you need to use a filter, 
preferably a V filter. Also, be sure to use the star labelled 119 on the chart as 
your comp star and use the others as check stars. The 119 star is also red, but 
not as much, so it will provide more accurate photometry for untransformed 
observations. The 119's B magnitude is 12.956 +/- 0.033 .

 Observers should begin practicing on the object right now to make sure you can 
achieve the required level of precision. Try to get 0.01 mag precision to look for 
structure in the transit light curve. 

=== Sign Up!

 Please observe as much as possible during the 3 days. We are creating a list on 
our web site of observers who can participate and during what windows they can 
observe. Please sign up by e-mailing with:

 Name, observer code, location, time zone and when you can observe. 

 This will help us coordinate observations between observers. Weather has been 
a real challenge with prior observations of this object so we need multiple people 
observing from multiple locations around the globe. 

=== Coordination

 A web page will be setup and maintained during the campaign:

  [obsolete link; page is at ]

 The campaign will be coordinated via the web page and the AAVSO-Photometry 
Discussion Group. Visit the web page for links to the discussion group archives, 
updated light curves, progress reports, links to charts and more information. If 
you plan to participate in the campaign send us a note and we'll put you on the 
web page.

 During the campaign itself we may setup a chat server for observers to 
participate in.

 This transit would be of GJ 876b, the first (outer) planet discovered in the 
system. Details on the system and other transit results can be found at

 The results of this transit will be combined with other transit results and research 
and submitted for publication. All observers who contribute significant photometry 
to this effort are welcome to be listed as co-authors of the manuscript.

 Note: IL Aqr was also the subject of Alert Notice 281 issued on May 11, 2001 
and CCD Views Vol. 1 No. 1 for June, 2001. 
 If you have any unsubmitted data from those publications please submit them 
as soon as possible. They may be very valuable!


Information on submitting observations to the AAVSO may be found at‭:‬

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