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Fwd: XRT (and EIS?) obs of stars

(Note, I tried sending this to eis_co@solar.isas.jaxa.jp, but it bounced ... please let me know if that address has been working for you.) 

Hello EIS folks, 

Earlier, I had forwarded some messages about potential stellar observations for EIS and XRT to Brooks and Williams.  I am now forwarding a couple of other messages from SAO stellar people.  One of them includes a calendar of potential dates for observations.  For these events, we can coordinate to plan things out ahead of time perform the appropriate calculations.  


hi Leon,

sorry, I didnt get your message right away due to an cerebral blockage in my
mailer.  Hence my message partially dittoing yours.

I could, on say, a monthly basis, do a "look-ahead" scan of the solar path
in the sky to look for strong, steady Xray sources which will pass thru the
XRT FOV.  They need not be eclipsed by the Sun, since passing thru the
off-limb polar regions would be interesting as well, I would think.
Sound worthwhile?  I think it is worth an experiment at some point at least.


Begin forwarded message:

From: Peter Smith <plsmith@cfa.harvard.edu>
Date: November 28, 2006 3:00:06 AM JST
To: Steve Saar <saar@head.cfa.harvard.edu>
Subject: XRT (and EIS?) obs of stars

Here are some possibilities:

Crab Nebula  ~ June 14    (almost 5 Rsun away, but maybe worth the effort)
I Gem  about June 21   G5 III
WY Gem     June 23    K5
Rho Leo      Aug 28    B1 I
CN Leo       Sep 4      Cataclysmic Variable
HD144608  Nov 25   G3 III
Nu1 Sgr     Jan 1      K2 V
HD206301  Feb 10   G2 IV
38 Aqr    Feb 19

I haven't checked trajectories well, but 38 Aqr and Rho Leo should pass
behind the sun.


Steve Saar wrote:
hi again,
it seems that since omega sco is not a major Xray source, if XRT misses it it is not a great loss.  (Its more useful for the EIS folks, given its UV continuum).  We should definintely be on the lookout for other stellar eclipses tho- any source with a nice, well defined Xray continuum could potentially be used as a flashlight thru solar coronal structures, which would
absorb the stellar Xrays in selected lines, permitting diagnosis of the absorbing solar features (densities, temperatures, sizes) in the best cases.
Is there any quicky program that predicts the RA DEC of the sun for any give date/time?  One could potentially cross match this with eg, the Rosat catalog to look for bright Xray eclipsers.
Mime-Version: 1.0 (Apple Message framework v752.3)
Cc: Steve Saar <saar@head.cfa.harvard.edu>, Leon Golub 
Content-Transfer-Encoding: 7bit
From: Loraine Lundquist <llundquist@cfa.harvard.edu>
Subject: Re: XRT (and EIS?) obs of omega Sco
Date: Mon, 27 Nov 2006 21:03:41 +0900
To: Peter Smith <plsmith@cfa.harvard.edu>


I regret to say that our observation table for omega Sco was  interrupted due to errors by XRT.  We will note the times for the  other stellar observations -- but please remind us again when they  come around.


On Nov 23, 2006, at 2:50 AM, Peter Smith wrote:

Leon, Ed, Mark:

I've refined my calculations (but am still working from  interpolations on
a paper plot).

Omega Sco enters extreme NE corner of FOV at ~02:15 UT on November 25
Omega Sco passes behind the sun at position angle 21.3 degrees (about
     eleven o'clock) at ~5:50 UT
Omega Sco reappears at PA -40.6 (about one thirty o'clock) at  ~13:00 UT
Omega Sco leaves the FOV at ~15:00, at which time it is about 0.75
     solar radii (Ro) above Sun center.

Assumption: FOV is 32 arcmin square

John Raymond says that Omega Sco is likely to have a soft x-ray  spectrum.
He and I don't know our way around the ROSAT catalog: he suggests that
we ask Steve Saar for an opinion.

Omega Sco moves one solar diameter in ~12.75 hours: 2.5 arcsec/sec.

I don't know how big EIS's "slots" are, but I were EIS, I'd position a
slot about 0.1 Ro above the limb for 2 one-hour periods:
  04:30 - 05:30 UT 0.6 Ro to east, 0.9 Ro to north
  13:30 - 14:20 UT 0.8 Ro to west, 0.75 Ro to north
and let the star drift across the slit.

If this doesn't work, we should remember 38 Aqr (~Feb 20) and rho Leo
(~30 Aug).  These are O or B; I don't know whether the have a soft X-
ray spectrum.

And there are some cooler stars suggested by John.  I'll talk to  Steve.


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          Peter L. Smith - Harvard-Smithsonian Center for Astrophysics
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          Peter L. Smith - Harvard-Smithsonian Center for Astrophysics
            60 Garden Street, MailStop-50, Cambridge, MA, 02138 USA
                 office: 617-495-4984  -  mobile: 617-851-6924