Re: Rapport från en balkong!
Posted: 2011-07-29 11:43:06
Jo nog var den ny...tror jag... men jag vet inte om Hemlin rapporterade in den.
Jag omnämde att han upptäckt den i BAA:s variabel forum.
Vi får väl försöka följa upp den i höst och vinter.
Här lite mer info från John BAA:s forum (glömt efternamnet) om Hemlins objekt:
http://www.fredda-o-ac.se/KPO/newmiravul.htm
The object has colours in red and 2MASS suitable for a red long period
variable, and it is an MSX6C infrared source, which fits.
So, depending on the latest CCD images it might be a semiregular or
such, of moderately low amplitude, but it is very likely not a Mira.
The 1951 plate looks to be an O plate, that's blue sensitive film, no
filter. The 1988 plate is assuredly a J plate with appropriate blue
filter. The red suspect object either does not or barely appears on
them. The 1990 plate is not in Aladin, so I'll just have to guess at
it being a blue plate.
The 1991 plate shows the object, because it is a red sensitive F plate
with yellow filter. The 1992 is again not in Aladin, but the general
look of it in its entirety, using all the stars, shows it to be very
similar to the 1994 plate which is an N plate, that is a near infrared
sensitive plate meant to be vaguely equivalent in sensitivity to
Johnson I (if I remember rightly, and that's Johnson, not Cousins or
Kron I).
The 1996 plate is not in Aladin but looks to be a red plate too, and
in this instance the relative difference in brightness in comparison
to adjacent stars between it and the 1991 plate appears to confirm
that there is at least a magnitude or two of variability.
Blue has to be compared with blue, red with red, and near infrared
with near infrared. Only the 1991 and 1996 plates give likely
confirmation of variability.
Going on to consult the USNO NOFS plate server shows that the 1996
plate is indeed a red F plate. There's also a 1951 E plate, as the
1950s usually had a near contemporaneous O (blue) and E (red) plate
pair (one taken immediately after the other). E is filtered, but
usually they weren't as deep as later F plates, nor quite the same
plate emulsion (I believe the letters denote which subtype of Kodak
photographic emulsion they are using). So you could add that plate to
the 1991 and 1996 F plates for three red plates, but you'll find it
doesn't match them as well as they match each other, in terms of field
stars.
Also the 1992 plate is indeed an infrared N plate and the 1990 plate
is a blue J plate, again via the plate and pixel server at nofs.navy.mil.
Summary : It is a red star, and it has a good chance of being
variable, but it is unlikely to be a Mira given the relatively low
archival amplitude. CMC14, dated near 2000, also gives it a red mag
of around 16, for instance.
h.g.
Jag omnämde att han upptäckt den i BAA:s variabel forum.
Vi får väl försöka följa upp den i höst och vinter.
Här lite mer info från John BAA:s forum (glömt efternamnet) om Hemlins objekt:
http://www.fredda-o-ac.se/KPO/newmiravul.htm
The object has colours in red and 2MASS suitable for a red long period
variable, and it is an MSX6C infrared source, which fits.
So, depending on the latest CCD images it might be a semiregular or
such, of moderately low amplitude, but it is very likely not a Mira.
The 1951 plate looks to be an O plate, that's blue sensitive film, no
filter. The 1988 plate is assuredly a J plate with appropriate blue
filter. The red suspect object either does not or barely appears on
them. The 1990 plate is not in Aladin, so I'll just have to guess at
it being a blue plate.
The 1991 plate shows the object, because it is a red sensitive F plate
with yellow filter. The 1992 is again not in Aladin, but the general
look of it in its entirety, using all the stars, shows it to be very
similar to the 1994 plate which is an N plate, that is a near infrared
sensitive plate meant to be vaguely equivalent in sensitivity to
Johnson I (if I remember rightly, and that's Johnson, not Cousins or
Kron I).
The 1996 plate is not in Aladin but looks to be a red plate too, and
in this instance the relative difference in brightness in comparison
to adjacent stars between it and the 1991 plate appears to confirm
that there is at least a magnitude or two of variability.
Blue has to be compared with blue, red with red, and near infrared
with near infrared. Only the 1991 and 1996 plates give likely
confirmation of variability.
Going on to consult the USNO NOFS plate server shows that the 1996
plate is indeed a red F plate. There's also a 1951 E plate, as the
1950s usually had a near contemporaneous O (blue) and E (red) plate
pair (one taken immediately after the other). E is filtered, but
usually they weren't as deep as later F plates, nor quite the same
plate emulsion (I believe the letters denote which subtype of Kodak
photographic emulsion they are using). So you could add that plate to
the 1991 and 1996 F plates for three red plates, but you'll find it
doesn't match them as well as they match each other, in terms of field
stars.
Also the 1992 plate is indeed an infrared N plate and the 1990 plate
is a blue J plate, again via the plate and pixel server at nofs.navy.mil.
Summary : It is a red star, and it has a good chance of being
variable, but it is unlikely to be a Mira given the relatively low
archival amplitude. CMC14, dated near 2000, also gives it a red mag
of around 16, for instance.
h.g.
