[vsnet-chat 3114] Re: LMC V1341 prelim sequence

[Mati Morel <morel@ozemail.com.au>]

At 07:41 PM 6/18/00 -0700, you wrote:
>     My thanks to John for extracting the magnitudes from the UCAC catalogue
>for the field near LMC V1341.  I have done what was suggested in my earlier
>post, by finding the mean offset of the UCAC magnitudes compared to V and then
>applying that offset to stars closer to the variable.  As John points out this
>is not necessarily going to be perfect.  However, because the four-fold
>overlap of the UCAC frames will yield some averaging, and because northern
>Chile is practically cloudfree for several months centered right in "LMC
>season" (austral summer), it is near-certain that the LMC images were taken in
>photometric conditions and that the internal consistency is likely to be high.

(snip)

>
>I looked up each of the sequence stars and those John found close to V1341 in
>USNO-A2.0 to look at their relative colors (and add the final decimals to the
>coords for the new ones).  None of the new stars is especially red, so I have
>simply added 0.34 to the UCAC values to get a reasonable 'mv', which I show in
>the second table below.

(snip)
>=============================================
>
>Name              1UCAC     V/B-V    V offset

>LMC V1341 Field Stars
>                       (2000)         UCAC(r)   mv    color
>GSC 9169-1555   5 09 04.9  -71 43 01   10.16   10.5   blue
>GSC 9169-1568   5 09 45.9  -71 37 47   12.01   12.3   med
>GSC 9169-1064   5 09 42.6  -71 47 16   12.86   13.2   med
>1UCAC           5 11 51.4  -71 38 50   14.19   14.5   med
>1UCAC           5 09 51.1  -71 34 00   15.13   15.5   blue
>


Hi all,
        As I produced the original chart for LMC V1341 in 1990, I should
jump in and
see how it can be updated. The first two stars in Brian's sequence above
_do_ have published UBV data. As follows : -

GSC 9169-1555 = P2856 :  V = 10.71; B-V +1.56, U-B +1.83  (Table 2)
GSC 9169-1568 = P2858 :      12.40      +0.52      -0.03  (Table 3) 
  
This data is taken from Grothues et al (Astron. Astrophys. Suppl. (1997)
121, 247).
This paper and a companion paper (Gochermann et al Astron. Astrophys. Suppl.
99,591)
provide very extensive photometry for _foreground_ stars in the direction of
the LMC.
Table 2 gives better photometry; Table 3 data is said to be a slightly less
reliable.
No coordinates are given for any of the hundreds of stars measured. For
that, one must
refer to earlier papers by 
--Fehrenbach and Duflot 1970, A&A Spec. Suppl. 1,1 and continuations
--Fehrenbach and Duflot 1981, A&A Suppl. 46,13-19
--Fehrenbach and Duflot 1982, A&A Suppl. 48,409-442

These authors produced several different lists, prefixed P,G,S,C.. We are
only concerned
here with their "Liste P" (galactic foreground stars).

I don't know if the two sets of papers are linked (or can be linked) online.
Would sure
simplify extraction of quality data.

Cheers,
  
/Mati

  /=====================================\
  |  MOREL ASTROGRAPHICS                |
  |  Stellar Data & Information Centre  |
  |  c/o M. Morel                       |
  |  6 Blakewell Road,                  |
  |  Thornton  NSW 2322  AUSTRALIA      |
  |  Tel./fax: (02) 4966 2078                                   |
  |  151d38'33" E, 32d46'47"S           |
  |  e-mail: morel@ozemail.com.au       |
  \=====================================/

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp