Eta Carinae: The 2003.5 Observing Campaign

"They finally came together in a fearful last death grip, in the midst of thick clouds and tempestuous elements; they fell to the ground with such force that they shook the whole world."
SPEELYAI FIGHTS EENUMTLA, From: George Benson Kuykendall, 1889, in History of the Pacific Northwest: Oregon and Washington, Volume II, Part VI, Elwood Evans, North Pacific history company, Portland, Oregon, pp. 60-95. Reprinted in: Clarence B. Bagley, 1930, "Indian Myths of the Northwest", Lowman and Hanford Co., Seattle, WA.

Relation of the X-ray Minima to the Historical Visual Lightcurve

In 2003.5 Eta Carinae, one of the most luminous and massive stars in the Universe, is expected to undergo an X-ray eclipse. This X-ray eclipse is believed to occur every 5.52 years and is apparently correlated with the 5.52 year fading of high excitation lines (like He II 10830 Å published by Augusto Damineli). The X-ray emission is thought to arise at a shock front produced as the wind from Eta Car slams into the wind from a less massive (but hotter) companion star. The eclipse may be produced as the shock front around the companion moves behind the thick wind of Eta Car. The upcoming eclipse marks only the 3rd time the X-ray eclipse has been seen (the first time was a fortuitous observation with ROSAT), and we hope will mark the first time the event is observed by the full complement of ground-based and space based instrumentation. This page summarizes some of the planned observations, and results as they become available.

Papers & Presentations relating to the 2003.5 Campaign


X-ray & Gamma-Ray Observations

See the X-ray Report for more detailed information about the current status of the X-ray observing campaign

The graph below shows the variation of X-ray emission from Eta Car; the red line shows the expected behavior of the observed X-ray emission if the emission were strictly periodic.

Eta Car RXTE Lightcurve

The figure below shows the observed RXTE data from a 1-year interval around the eclipse in 1998 (top) and the expected X-ray lightcurve in a 1 year interval around the 2003.5 eclipse (bottom). Note that we already see deviations in the x-ray behavior compared to last cycle - it's not yet clear what effect these deviations will have on the 2003.5 "event".

Observed and Expected X-ray variation

The discussion of the X-ray observing plan as it stood in July 2001 and as presented by MFC at the Eta Car: Reading the Legend Workshop (Mt. Rainier, WA, July 10-14 2001) is now available.


500 ksec of Chandra time has been awarded (PI: Mike Corcoran) to observe Eta Car with the HETGS (5 pointings of 100 ksec each) to sample all the important phases of the variation during the next X-ray eclipse. The scheduled phases for observations can be seen above. The sequence numbers for the 5 pointings are 200219, 200218, 200217, 200216, and 200215.
A) Observation 200219 was observed on October 16, 2002
B) Observation 200215 was observed on May 3, 2003
C) Observation 200218 was observed on Jun 16, 2003
D) Observation 200216 was observed on Jul 20, 2003 
D1) Observation 200237 was observed on Aug 28, 2003
E) Observation 200217 was observed on Sep 26, 2003


We will continue our monitoring of Eta Car with RXTE through the X-ray eclipse to enable us to compare in detail the lightcurve shape with the previous cycle. The current schedule of RXTE observations of Eta Car is available here. You can also see the recent RXTE lightcurve. Contact Mike Corcoran if you'd like to receive e-mail notices whenever the RXTE lightcurve gets updated.


  1. 5 observations of 8300 seconds each were approved to observed the spectral variation of the star prior to the X-ray eclipse:
    1. 0145740101 8300 2003-01-25@12:40:12
    2. 0145740201 8300 2003-01-27@00:45:34
    3. 0145740301 8300 2003-01-27@20:18:56
    4. 0145740401 9800 2003-01-29@01:22:23
    5. 0145740501 8300 2003-01-29@23:36:58
  2. 2 TOO observations have been granted to observe the X-ray eclipse ingress:
    1. 41200 sec on 2003-06-08@12:42:14
    2. 32700 sec on 2003-06-13@23:33:50
  3. Observation 14578 (ObsID 0145780101 an AO2 triggered observation during eclipse) has been scheduled in revolution 662, i.e. start at 2003-07-22@01:33:19.
  4. 3 AO3 observations to study the change in the X-ray spectrum during recovery have been accepted:
    1. 0160560101 2003-08-02T20:42:53
    2. 0160560201 2003-08-09T01:25:59
    3. 0160560301 2003-08-18@15:05:13


200 ksec of INTEGRAL time has been awarded (PI: Dr. Yousaf Butt, Center for Astrophysics) to observe Eta Car in Gamma rays during the X-ray eclipse. This observation has been amalgamated with a 1 Msec "core" program to observe the Carina Nebula, so that the team will have access to a total of a million second observation on Eta Car.

Date: Mon, 23 Jun 2003 14:08:12 +0200

Dear Integral Observer,

Your  observation belonging to proposal 0120039 has been 
scheduled as follows:

Start time (UTC)    | Source       | RA (J2000) | Dec (J2000)
2003-06-24 18:55:33 | eta Carinae  | 10:45:03.6 | -59 43 03.0 
End time
2003-06-28 08:53:30

Total elapsed duration 200200sec

For more details we refer to the Integral short-term plan on the
web, available on:

June 25 Update: The INTEGRAL observation has been split into two 100 ksec observations, one on June 24 and one on July 3 in order to study the variability of the source after the beginning of the X-ray minimum.

HST Treasury Observations

A "Treasury" proposal for STIS monitoring of Eta Car during the upcoming X-ray eclipse has been approved (PI: Dr. Kris Davidson, University of Minnesota). The following figures show the current observing plan based on Dr. Ted Gull's (NASA/Goddard Space Flight Center) e-mail of 25 January.

See the Eta Car HST Treasury Website at

Ted Gull has provided the schedule of HST Treasury observations

The figure on the left shows (approximately) the distribution of STIS observations as a function of X-ray phase, compared to the RXTE X-ray lighcurve. The figure on the right shows the distribution of STIS observations vs. phase compared to 2 published radial velocity curves, one by Damineli et al. (2000) and one by Corcoran et al. (2001).

stis plan

Infrared Observations

(IR Report) Dr. Patricia Whitelock (South African Astronomical Observatory) kindly sends along the following concerning IR broad-band monitoring of Eta Car from South Africa:
Date: Sat, 18 Jan 2003 18:33:41 +0200 (SAST)
From: Patricia Whitelock 
To: "Michael F. Corcoran" 
cc: MWF , ,
   Patricia Whitelock 
Subject: Re: Eta Car RXTE monitoring through Jan 15

Hi Mike

I expect we will be able to monitor eta Car in JHKL as follows:
January 21 - 31,
February 1 - 3, 18 - 28,
March 1 - 3, 11 - 17,
April 15 - 28,
May 13 - 19,
June 3 - 30.
That is the end of the current allocation period. I will apply
for time in July as well of course, but will not know about that
for a few months.

It is our intention to get one JHKL observation per night whenever


Dr Patricia Whitelock                                         
Acting Director                                               
South African Astronomical Observatory                        
P O Box 9                               Phone: +27 21 4609318
7935 Observatory                        Fax: +27 21 4473639   
South Africa                            email: 

Millimeter Observations

(Millimeter Report) Dr. Zulema Abraham ( IAGUSP) reports:
From: "Zulema Abraham" 
Subject: Re: Eta CAr is dissapearing at the 7 mm continuum also
Date: Mon, 23 Jun 2003 18:34:00 -0200

Hi Mike
        I will be observing every day, weather allowing


Radio Observations

Dr. Stephen White from the University of Maryland writes:
Date: Wed, 21 May 2003 13:36:07 -0400 (EDT)
From: Stephen White 
Subject: Eta's radio light curve

The 8 GHz radio light curve and movie at
have been updated for an Australia Telescope Compact Array
observation last week (the observation was shorter 
than usual so the image is not quite as good as the others). The radio flux
continues to be markedly lower than at the same stage of the previous cycle
and may bottom out below the last minimum, but possibly not below the previous 
minimum. Observations are now possible at 22 GHz as well, and the preliminary
images show in addition to the main source identified with the star/s a 
bright second source 0.5 arcsec to the west-north-west.

Stephen White, Bob Duncan, Jessica Chapman and Baerbel Koribalski.

Date: Wed, 17 Apr 2002 18:31:58 -0400 (EDT) From: Stephen White Subject: radio evolution of Eta X-Sun-Charset: US-ASCII We have updated the radio light curve and movie for Eta Carinae at with the most recent observation being last week. The radio flux is about half what it was at the same stage of the previous cycle: we interpret this as less ionizing flux getting out to the outflowing gas on this side of the system. Stephen White and Bob Duncan

Ground Based Optical Spectrometry and Photometry

Please send any additions or corrections to Mike Corcoran.

Page Author: Dr. Michael F. Corcoran
Last modified Friday, 23-Sep-2005 12:01:30 EDT