[vsnet-newvar 496] re Haseda variable (HadV62)

[no name <crawl@zoom.co.uk>]

I have been examining plate images of the field from the USNO NOFS PPM
archive server.

The first thing I've noticed is that the USNO A2.0 blue minus red colour
is spurious.

Although red and blue plates exist for both mid 1974 and mid 1986, the
magnitudes derived are from a blue 1974 plate and a red 1986 plate.

Examination of the blue and red plates for 1974 shows that the object
was equally faint in blue and red plates at that time [though it is
difficult to identify, sitting atop a column of 4 or so similarly quite
faint stars].

Examination of the blue and red plates for 1986 shows that the object
was quite a bit brighter at that time than in 1974, and by eye about
equally so in red and blue.

From other plates, the object was probably near the current level in
both blue and red plates at 1951.6, and fairly bright in blue and red
plates at 1950.5.

It was near the current brightness in 1991.7, in both blue and red
plates, and also quite bright in red and blue plates of 1992.4.

Interestingly, the Tycho2 magnitude of around 11.5 V [although this
could be out by up to a magnitude or more] for this object suggests that
it was visible between 1989 and 1991, when the Hipparcos spacecraft's
Tycho experiment was recording data. Unfortunately no epoch photometry
is available for Tycho2, and the catalogue does not state how many
observations make up the BT and VT magnitudes, but their scatter are
only 0.13 and 0.17 respectively.  [ie Was it pretty constant
throughout?]

The UCAC1 magnitude of 12.5 of mean epoch 1999.45 shows the object was
bright around that time.

Taichi Kato noted that the proper motion might be due to a confusion
with another star.

The UCAC1 catalogue notes that 2 catalogue positions were used in
derivation of the proper motion.  As this object is in few catalogues,
and Tycho2 wasn't used in UCAC1, I'd _surmise_ the two positions are the
UCAC1 one and an USNO Ax.0 one.

However, the _current_ UCAC1 position is _north_ and east of the USNO
A2.0 position, whereas the proper motion in declination is given as
negative.

Given the USNO Ax.0 spurious colours, due to the objects variability,
the only hint as to colour is still that from Tycho2, which is around
B-V 0.3: most unMira-like.  Meanwhile, HadV62 seems to often be quite
bright about mid-year [though not in 1974, when it was quite faint],
which suggests a Mira with a not uncommon period of about a year or so.
(Being in the "Teapot"'s lid, it'll be at it's best midsummer anyway).

Then again, Tycho2 notes it as a bright object of little scatter, which
suggests it may have stayed bright for quite some time between 1989 and
1991, ie _not_ very Mira like.

Its absence from the GSC, and the lack of any candidates in ROSAT and
IRAS catalogues is not necessarily meaningful, as the V 8.0 star at ~
80" could be a problem.

As Dr Kato notes, this'll only be resolved with new observations ;)

Cheers

John

VSNET Home Page

Return to Daisaku Nogami

---

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