Globular Cluster Messier 5 in Serpens
M5 is about 24500 LY away and contains at least 100000 stars. It is 165 LY across and is one of the larger globular clusters to orbit our galaxy.
Probably the core remnant of a small dwarf galaxy largely devoured by our galaxy, it is about 13 billion years old and contains a large number of variable RR Lyrae type stars. These are similar to Cepheid variables and have a luminosity/period relationship that can be used to precisely estimate their distance.
Serpens is quite low in the sky for me and M5 only just brushed over my neighbour's rooftop. I managed 6 x 10 minute subs before cloud crept in. There was quite a strong background gradient.
The large star nearby is 5 Serpens.
Equipment-
480/80mm f/6 Altair Starwave triplet refractor.
Altair Planostar 1.0 x FF with 2 inch IDAS LPS D1 filter
Astro-modified Canon 80D at ISO400; 6 x 10 minute subs (60 mins total integration).
NEQ6 Pro Mount with Rowan modified belt drives. 1-star align.
Laptop with BackyardEOS for focusing and acquisition.
Calibration-
60 dark frames - sensor temperature matched from Dark Library (17c)
80 bias frames
60 flat frames (Electroluminescent panel @ 1/40s)
QHY Polemaster alignment -
Error measured by PHD2= 1.3 arc minute.
RA drift +1.75 arcsec/min
Dec drift +2.70 arcsec/min
Guiding-
PHD2 guiding with ZWO ASI290mm/Altair lightwave 209/50mm secondary scope. Alternate subs dithered.
RA RMS error 0.88 arcsec, peak error -3.50 arcsec
Dec RMS error 0.60 arcsec, peak error 3.32 arcsec
Astrometry-
Center (RA, hms): 15h 18m 31.213s
Center (Dec, dms): +2° 14' 36.94"
Size: 85 x 61 arcmin
Pixel scale:1.59 arcsec/pixel
Light Pollution-
SQM (L) at middle of session (0140 hrs UT) 20.48 mag/arcsec2 Typical of rural/suburban edge - Bortle scale = 4/9 Green/Yellow
Environmental-
Temp =11.8c
Humidity = 55%
Dew point = 4.2c
Light cloud, 2 subs lost to cloud - session terminated.
Post processed in PixInsight 1.8.
Globular Cluster Messier 5 in Serpens
M5 is about 24500 LY away and contains at least 100000 stars. It is 165 LY across and is one of the larger globular clusters to orbit our galaxy.
Probably the core remnant of a small dwarf galaxy largely devoured by our galaxy, it is about 13 billion years old and contains a large number of variable RR Lyrae type stars. These are similar to Cepheid variables and have a luminosity/period relationship that can be used to precisely estimate their distance.
Serpens is quite low in the sky for me and M5 only just brushed over my neighbour's rooftop. I managed 6 x 10 minute subs before cloud crept in. There was quite a strong background gradient.
The large star nearby is 5 Serpens.
Equipment-
480/80mm f/6 Altair Starwave triplet refractor.
Altair Planostar 1.0 x FF with 2 inch IDAS LPS D1 filter
Astro-modified Canon 80D at ISO400; 6 x 10 minute subs (60 mins total integration).
NEQ6 Pro Mount with Rowan modified belt drives. 1-star align.
Laptop with BackyardEOS for focusing and acquisition.
Calibration-
60 dark frames - sensor temperature matched from Dark Library (17c)
80 bias frames
60 flat frames (Electroluminescent panel @ 1/40s)
QHY Polemaster alignment -
Error measured by PHD2= 1.3 arc minute.
RA drift +1.75 arcsec/min
Dec drift +2.70 arcsec/min
Guiding-
PHD2 guiding with ZWO ASI290mm/Altair lightwave 209/50mm secondary scope. Alternate subs dithered.
RA RMS error 0.88 arcsec, peak error -3.50 arcsec
Dec RMS error 0.60 arcsec, peak error 3.32 arcsec
Astrometry-
Center (RA, hms): 15h 18m 31.213s
Center (Dec, dms): +2° 14' 36.94"
Size: 85 x 61 arcmin
Pixel scale:1.59 arcsec/pixel
Light Pollution-
SQM (L) at middle of session (0140 hrs UT) 20.48 mag/arcsec2 Typical of rural/suburban edge - Bortle scale = 4/9 Green/Yellow
Environmental-
Temp =11.8c
Humidity = 55%
Dew point = 4.2c
Light cloud, 2 subs lost to cloud - session terminated.
Post processed in PixInsight 1.8.