Subject: Re: [vsnet-chat 489] Re: Variable star near M27
Date: Fri, 1 Aug 1997 15:44:54 -0700
To: gianmasi@fr.flashnet.it

Grettings Gianluca. Your variable does not appear in the GCVS4 or
the NSV, as you noted, and does not appear in the IRAS source catalogue,
which red variables do (I think yours is too faint for IRAS). Did you not
see my earlier vsnet-chat posting about your star? Here is a more
complete note I sent to the sci.astro.amateur newsgroup:

Earlier today, the Italian amateur Gianluca Masi reported to the Japanese
variable-star 'vsnet' list-server that he'd found an apparently new variable
star near M27. The star is located close to 10' nearly due south of the
central star of the Dumbbell:

M27 central star: 19 59 36.3 +22 43 16 (2000)
new variable: 19 59 41.9 +22 33 50

In case the position doesn't get you there, Gianluca has two CCD frames posted
at his Web site:
http://www.eurolink.it/comets/varst.html
South is up and west to the left in these images. The position for the
variable comes from the USNO A1.0 star catalogue. This catalogue reports a
blue magnitude of 17.2 and a red magnitude of 13.7, The implied color index
of 3.5 suggests the star is a red variable, possibly a Mira, and thus is likely
to have a period of variation of some months. His two frames (taken about
seven months apart) show a magnitude range of no more than about 1.5
magnitudes. If this is something like the full amplitude, the likelihood is
that it's a semiregular variable with a cycle-length of a few months.
Since a lot of folks observe M27 with CCDs, it is likely that the star
appears on many images, and in fact the variability could be characterized
from data already available. If you'd like to try making an observing project
of this star, hit it about once per week for the rest of the observing season.
Use a standard photometric filter if possible (such as Cousins R) to take the
frames.

Hope this helps.

\Brian