(cba:news) [Fwd: GALEX observations of TT Ari]

Joe Patterson jop at astro.columbia.edu
Fri Nov 13 17:29:49 EST 2009

Dear CBAers,

Galex (an ultraviolet imaging/spectroscopy satellite) has scheduled some 
target-of-opportunity time for TT Ari, from now until Nov. 27.  Appended 
is the schedule.  Like nearly all science satellites, this is a 
low-Earth-orbiter, hence the windows are all somewhat brief - but there 
are many of them, and if you have clear sky coinciding with any of these 
times, your observations will have very high scientific value.  Under 
these circumstances, it might well be best to use filters, to get truly 
simultaneous measures of the continuum.  (Hard to say for sure, though; 
we'll know for sure after the data are in!)


-------- Original Message --------
Subject: GALEX observations of TT Ari
Date: Fri, 13 Nov 2009 10:45:15 -0800
From: Karl Forster <krl at srl.caltech.edu>
To: jop at astro.columbia.edu
CC: Karl Forster <krl at srl.caltech.edu>,	Chris Martin 
<cmartin at srl.caltech.edu>, kerry.d.erickson at jp.nasa.gov, 
susan.g.neff at nasa.gov

Hi Joe,

It was good to see you again. Thank you for sending the request for 
discretionary time for observations of TT Ari. I agree, it is a unique 
to explore this CV in a "zero accretion" state.

With Chris's approval I have scheduled some GALEX observations of TT Ari for
next week and will continue with more observations until we loose visibility
on November 27th.

Here is the schedule of observations:

Eclipse  Target_ID Survey OW_pos  Start                  End 
         Exposure (seconds)
  34933   TT_Ari       ETI imaging 2009-11-14T18:26:41.2Z 
2009-11-14T18:51:24.2Z 1480
  34940   TT_Ari       ETS   grism 2009-11-15T05:53:58.5Z 
2009-11-15T06:21:33.1Z 1650
  34941   TT_Ari       ETS   grism 2009-11-15T07:32:32.6Z 
2009-11-15T08:00:08.6Z 1650
  34954   TT_Ari       ETI imaging 2009-11-16T04:53:55.4Z 
2009-11-16T05:21:48.1Z 1670
  34955   TT_Ari       ETI imaging 2009-11-16T06:32:29.5Z 
2009-11-16T07:00:23.3Z 1670
  34969   TT_Ari       ETI imaging 2009-11-17T05:32:26.8Z 
2009-11-17T06:00:34.9Z 1680
  34970   TT_Ari       ETI imaging 2009-11-17T07:11:00.9Z 
2009-11-17T07:39:09.9Z 1680
  34983   TT_Ari       ETI imaging 2009-11-18T04:32:25.0Z 
2009-11-18T05:00:44.0Z 1690
  34984   TT_Ari       ETI imaging 2009-11-18T06:10:59.2Z 
2009-11-18T06:39:18.9Z 1690
  34998   TT_Ari       ETI imaging 2009-11-19T05:10:58.8Z 
2009-11-19T05:39:26.3Z 1700
  34999   TT_Ari       ETI imaging 2009-11-19T06:49:33.1Z 
2009-11-19T07:18:01.0Z 1700
  35013   TT_Ari       ETI imaging 2009-11-20T05:49:34.5Z 
2009-11-20T06:18:07.4Z 1710
  35014   TT_Ari       ETI imaging 2009-11-20T07:28:09.0Z 
2009-11-20T07:56:42.1Z 1710

Note: All time are UT

I also wanted to let you know that there have been a number of
GALEX exposures of TT Ari earlier in the mission:

Date       Survey  Target_ID           Exposure
2003-11-22  AIS    AIS_184_sg44         144s
2004-11-19  GII    GI1_113009_TT_ARI   1467s
2004-11-19  GII    GI1_113009_TT_ARI   1686s
2005-10-06  AIS    AIS_184_sg44         112s (NUV only)
2005-11-02  AIS    AIS_184_sg44         106s
2007-10-16  AIS    AIS_184_sg44         106s
2007-11-04  AIS    AIS_184_sg44          96s

Note that the GI observations were centered on the position of TT Ari
but the All sky survey observations placed the star approx 20 arcmin from
the center, still well within the field of view.

I noticed that the GI observations have a reflection feature in the
NUV exposure due to a star off the south edge of the field of view. To
avoid this I have moved the pointing center for the new observations
10 arcmin north. So TT Ari will be 10 arcmin south of the center of
the field of view.

I have also included a couple of grism exposures with dispersion
angles (PA East of North) 320 and 180 degrees.  This will avoid
confusion with spectra from some of the nearby bright stars.  All the
archive data is available at MAST:


except for the photon data which you will need if you want to explore
variations during an exposure (in the archived and new data we will

Let me know if you have any questions or need more information.



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