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[vsolj-alert 363] (fwd) BL Lac observing campaign

(fwd) BL Lac observing campaign

　６月末にASCAの観測に合わせてBL Lacの光学同時観測のキャンペーンが行われる
　予定です。満月期で地上観測はやや不利ですが、日本の経度は非常に重要で（天
　気は問題ですが・・）参加が望まれます。CCD測光により、時間分解能１分程度
　の連続測光ができれば観測可能です（フィルターの使用が望まれますが必須では
　ないようです）。

　もちろん、キャンペーン前から変動を調べておくことも重要です。

   Forwarded upcoming BL Lac observing campaign alert:

From TOSTI@astrpg.pg.infn.it Thu Jun 17 22:24 JST 1999
Date: Thu, 17 Jun 1999 15:27:14 +0200
From: <Gino.Tosti@PG.infn.it>
Subject: Next BL Lac Campaign

Dear All

As you  know ASCA will obseve BL Lac from  UT 5:26 on 
June 28 until UT 18:16 on June 30 
(ASCA PI is Makoto Tashiro - tashiro@amalthea.phys.s.u-tokyo.ac.jp) 
and a WEBT campaign will carred out simultaneously with  the ASCA 100 ks
pointing. 

As in the recent SAX/WEBT camping participating groups are asked 
to observe in at least two bands B/I or B/R, V/R, V/I  
Unfortunately the ASCA pointing will fall during the full moon period.  
these are the moom parameter calculated for Perugia
                        Phase   RA     DEC
Sun Jun 27/Mon Jun 28   99%   17 40.2 -20 19
Mon Jun 28/Tue Jun 29   100%  18 32.0 -21 01
Tue Jun 29/Wed Jun 30   99%   19 24.4 -20 45
Wed Jun 30/Thu Jul 01   96%   20 17.1 -19 32

To trigger the collaboration all people that can do it,  are ivited to start
monitoring of BL Lac 
next week and advise me about this.
This will allow uss to discover,  before the ASCA campaign,  
if  there are  some problems with data 
collected with different instrumentation, 
The instrumental  magnitude for  stars B,C,H and K  
( Bertaud et al. 1969, Astron. Astrophys. 3, 436, 
magnitudes for these star are  reported by Fiorucci & Tosti G., 1996, A&AS
116, 403  
for  the VRI  band  while for the B band we  the values reported by  
Bertaud et al. (1969, see above) should be used. 
) and BL Lac should be all measured using an aperture ( diameter ) of 10
arcsecs,  
and sent  me in the following format: 

    JD        UT     BLLAC          B         C           H           K    FILT  EXP AIR-MASS FWHM    OBS
            (start)                                                              (s)         (arcsec)
50000.0000   21:00   -1.00 0.01 -1.00 0.01 -1.00 0.01 -1.00 0.01 -1.00 0.01  I   300   1.00   3.0     PERUGIA

A brief comment on the instrumet, CCD camera and Filter shold be included in 
the header of the ascii data file.

Please send me a mail confirming our participation to the campaign.  
 Ciao Gino

---
From mattox@gamma.bu.edu Thu Jun 17 23:30 JST 1999
Date: Thu, 17 Jun 1999 10:18:10 -0400
From: John Mattox <mattox@gamma.bu.edu>
Subject: Re: Next BL Lac Campaign

Gino,

Svetlana Marchenko will observe BL LAC in B/I bands with high temporal
density on the Perkins telescope on June 28, 29, & 30 UT. On these same
nights, I will observe on clear nights with the Williams College 24" 
telescope in Western Massachusetts - see 
http://vsnet.williams.edu/Astronomy/Hopkins/

I expect that Svetlana may also be able to take a few BL LAC frames 
on the Perkins at the beginning and end of clear nights on the 24, 25, 
26, & 27th.

We have fixed the process on blazar so that E-mail sent to 
Blazar@gamma.bu.edu will be posted  within 60 seconds to 
http://gamma.bu.edu/pub/mattox/blazar/new_mail
This can be used for communications of general interest during the campaign.

Lets hope for remarkable variability, and clear skies!

Ciao,
John

---
From nesci@astro.uniroma1.it Fri Jun 18 00:05 JST 1999
Date: Thu, 17 Jun 1999 16:55:10 +0100
From: Roberto Nesci <nesci@astro.uniroma1.it>
Subject: BL Lac

Dear all,

A preliminary I-filter light curve of BL Lac is available at
http://astro.uniroma1.it/nesci/i.gif.
The BeppoSAX observation was succesfully and the source was detected both
in the MECS and in the PDS instruments. Quick look data show that the
sincrotron emission tail is present a low energies, while an inverse
Compton component comes up at higher energies. This is quite good.
A complete reduction with time resolved results must wait some time,
anyway,
The intranight obs. of BL Lac during the SAX pointing gives the opportunity
to check the intercalibration of the reference stars with different
telescopes/filters/cameras.
This is of importance also for the next campaign with ASCA. You can see
that some systematic difference exist and must be understood if high
precision color variations are to be studied, but are of low concern
for the overall behaviour of the source.

Here are the results for the I filter for the participating observatories:

            B-C    B-H    B-K    C-H    C-K    H-K   CCD
Lowell    -2.153 -1.923 -3.452  0.229 -1.299 -1.528  SITe
          -2.151 -1.927 -3.454  0.224 -1.303 -1.527

Abast.                          0.265 -1.290 -1.553a TC241 (ST6)^

Greve     -2.225 -1.955 -3.520  0.270 -1.295 -1.565  TC241 (ST6)
          -2.220 -1.948 -3.516  0.272 -1.295 -1.568

Perugia   -2.20  -1.95  -3.42   0.25  -1.22  -1.47   TC211 (Lynx)

The agreement is very good for different nights of the same instrument,
less good when different instrumental sets are compared. This certainly
due to different responses to red tail of the stellar energy distribution.
Indeed the V-I colors are as follows:
B= 1.78
C= 0.94
H= 1.33
K= 0.93
The C-K magnitude difference is the same for all telescopes, and indeed they
have the same V-I color index, while the other stars, which are much redder,
show detectable systematic effects.


Now the V filter. Data from Lowell, Abastumani, Vallinfreda.

Obs.      B-C      B-H     B-K    C-H     C-K     H-K
Lowell  -1.358  -1.540  -2.664  -0.183  -1.306  -1.123
        -1.349  -1.537  -2.655  -0.188  -1.305  -1.117

Perugia -1.36   -1.50   -2.57   -0.14   -1.21   -1.07

Abast.                          -0.170  -1.299  -1.135

Vallin. -1.341  -1.498  -2.636  -0.157  -1.295  -1.138 TC241 (ST6)

Think about that...

Roberto Nesci

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