Uwe Glahn
February 9th, 2014, 09:23 PM
Auner 1 (C 0702-196)
Canis Major
RA: 07 04 16
DEC: -19 45 00
Type: OC (2 II m)
Distance: 29000Lj
Size: 2,5’
With the beginning of the Palomar Observatory Sky Survey (POSS) in the early 50’s the number of cataloged objects rises tremendously. The plate center with a size of 5,4°x5,4° was of very high quality with only a few plate faults like dust particles or defects on the film emulsion. The only big problem were reflections within the Schmidt optics which produces more or less “ghosts”, especially at a location symmetrically opposite the plate center from a bright star. Behind these bright ghosts all objects were superimposed and no new discoveries were able to find. And this is the story behind the cluster Auner 1. The troublemaker is called “Sirius” which is only 5,5° NW.
1980 Austrian astronomers around Auner (http://adsabs.harvard.edu/abs/1980PASP...92..422A) searches more exactly especially in and around these ghosts and found a new cluster on the old POSS1-E plate. The confirmation gave the brand new ESO-B plate which was taken in La Silla. This plate shows no ghost at this position, because for the new plates the telescope was orientated differently.
Carraro et al (http://adsabs.harvard.edu/abs/2007AJ....133.1058C) classify Auner 1 as an old cluster of 3,25 Gyr. They associate Auner 1 to a very old star population which stand in a line of sight to the more distant population of the “Norma-Cygnus Spiral Arm”.
For all observers who thought open clusters were boring and too easy for bigger aperture are warned. Even in bigger telescopes a resolution of individual stars are difficult. The brightest stars are around 16mag, most of the cluster members are in the 17mag-19mag range. I know about a successful observation with 8” but even in a 16” telescope the cluster remains difficult to observe. But…
…"GIVE IT A GO AND LET US KNOW"
GOOD LUCK AND GREAT VIEWING!
15'x15' RGB with R=POSS1-E; G,B=POSS1-O
1084
15'x15' RGB with R=SERC-J; G,B=AAO SES
1085
Canis Major
RA: 07 04 16
DEC: -19 45 00
Type: OC (2 II m)
Distance: 29000Lj
Size: 2,5’
With the beginning of the Palomar Observatory Sky Survey (POSS) in the early 50’s the number of cataloged objects rises tremendously. The plate center with a size of 5,4°x5,4° was of very high quality with only a few plate faults like dust particles or defects on the film emulsion. The only big problem were reflections within the Schmidt optics which produces more or less “ghosts”, especially at a location symmetrically opposite the plate center from a bright star. Behind these bright ghosts all objects were superimposed and no new discoveries were able to find. And this is the story behind the cluster Auner 1. The troublemaker is called “Sirius” which is only 5,5° NW.
1980 Austrian astronomers around Auner (http://adsabs.harvard.edu/abs/1980PASP...92..422A) searches more exactly especially in and around these ghosts and found a new cluster on the old POSS1-E plate. The confirmation gave the brand new ESO-B plate which was taken in La Silla. This plate shows no ghost at this position, because for the new plates the telescope was orientated differently.
Carraro et al (http://adsabs.harvard.edu/abs/2007AJ....133.1058C) classify Auner 1 as an old cluster of 3,25 Gyr. They associate Auner 1 to a very old star population which stand in a line of sight to the more distant population of the “Norma-Cygnus Spiral Arm”.
For all observers who thought open clusters were boring and too easy for bigger aperture are warned. Even in bigger telescopes a resolution of individual stars are difficult. The brightest stars are around 16mag, most of the cluster members are in the 17mag-19mag range. I know about a successful observation with 8” but even in a 16” telescope the cluster remains difficult to observe. But…
…"GIVE IT A GO AND LET US KNOW"
GOOD LUCK AND GREAT VIEWING!
15'x15' RGB with R=POSS1-E; G,B=POSS1-O
1084
15'x15' RGB with R=SERC-J; G,B=AAO SES
1085