Sep_15_1999_M55.txt Shift M55 
        Start at 1999:258:20:00 GMT = 1999 Sep 15 04:00pm EDT
        End                           1999 Sep 15 10:00pm EDT

   
SOT Lead	Ed Kellogg
FOT-SI		
ACIS		Yousaf Butt
HRC-SI		

(Times: hhmm or ddd:hhmm, not precise.)

Plan: continue HR1099 observation

EVENTS							DONE	OBSID
--------------						----	-----
AOS							2000	62538
LOS							0005	62538

NOTES/ISSUES/PROBLEMS 
--------------------- 
S/C state at 2033:

       PCAD MODE= NPT
       Stars:	= 5
       FIDS	= 3
       RA	= 54.2135 (estim.)
       DEC	= 0.5751 (estim.)
       ROLL	= 100.2724 (estim.)
       Format	= 2
       OBSID	= 62538
       SIM FA	= -467
       SIM TSC	= 75615 (ACIS-S)
       HETG	= 6.7, 7.8 degrees
       LETG	= 81.7, 79.8

2300: A very bright x-ray source - too bright for Chandra to look at!
I just got a call from Martin Weisskopf of MSFC Project Science. They
just received an advance copy of an IAU circular by Smith, Levine and
Morgan about a very bright transient x-ray source.

Its location is J1819.3, -2525, which converts to RA = 270.32, Dec =
-25.42.  Martin described it as 12 x Crab in intensity.

This source was reported previously in IAU circular 7119 by J in 't
Zand et al as Sax J1819.3-2525 observed Feb 20, peaking at 80
mCrab. It is located near GM Sgr, a variable star, proposed as the
identification. Sax position is 18 19 20, -25 24.9 with a 2' 90% conf
radius.

It was also reported in IAU 7120 by C. B. Markwardt et al as XTE
J1819-254 on Mar 1 with a position consistent with the Sax source,
varying between 3-37 mCrab.

I calculate galactic coordinates based on the Sax position are l =
7.13, b = -4.59, very near the galactic center.

I called Alan Levine of MIT. He gave me more info:

This transient varied over the day today as follows:

UT	I(Crab)
--	-------
0200	0.05
0600	1.5
1500	12.
1600	disappeared (eclipse?)

We should make sure that Chandra doesn't inadvertently maneuver by
this source, or observe it, since the intensity could be much too
bright for our detectors.