Saturday, October 10, 2015

QHY6 for guide rescue

QHY6 camera
I must say I like off-axis guiding during astrophotography. It provides uncompromised stiffness, but at some cost. Off-axis guider field of view is very modest, and sometimes it is not so easy to find bright enough star to hook on. That's why quite sensitive and preferable cooled camera is wanted for OAG. Using ASI120 I was happy almost in all cases except a few when I needed to reframe my picture to find a star to guide. So I decided to test QHY6 camera in that role also sold at ALccd-QHY6 name by astrolumina.de . 
Compared to ASI120MM
Camera is equipped with peltier cooling that drops sensor temperature about 24C below the ambient. Neither cooling power nor temperature cannot be controlled. Cooling fan is very quiet, and temperature stabilizes quickly. Camera drivers at both 32 and 64 bit windows machine have been installed without any problem, and camera has started at first connection. Camera drains 0.3A from the 12V power supplier, so it is not power hungry.
First night tests showed that camera is quite sensitive. 5 seconds exposure with TS13/910 refractor recorded stars as faint as 15mag. Stars brighter than 14.5mag has SNR better than 10, so they can be used for guiding.
5 seconds exposure with QHY6 camera
I am quite happy with the camera sensitivity, comparing to ASI120MM it is better about 2.5-3mag. It is especially obvious when ambient temperature is quite high. 

Pros:

  • it is small and lightweight
  • does not require much power 
  • can be supplied only with 5V from USB port (then it is not cooled)
  • it is fast (USB2) so image is beeing read quickly
  • no problems with windows 7 32 and 64 bit
Cons:
  • it is interlaced camera, so saturated images needs to be deinterlaced
  • pixel is not square - 6.5x6.25um
  • there is no control for colling - on or off
  • sensor chamber is not sealed, so frost can occur at high humidity (over 90%). Hovewer there is a place in camera body to put dessicant bag
Sample bias frame

Sample 300s dark frame
Clear skies!

Thursday, October 8, 2015

M29 - so obscured

Messier 29 is yet another open star cluster in the Cyngus constellation. Its stars belongs to the Cygnus OB1 association. Five brighters stars of this cluster is giants of B0 spectral type - its absolute magnitude is about -8mag, so each one is 160000 times brighter than the Sun. The M29 cluster is quite modest, its brightest members have visual magnitude fainter than 8mag, but if there would be no Milky Way dusts between the cluster and us, these stars would be 1000 times birghter than they are now. The distance to this cluster is not well determined - according to different sources it is something between 4000 and 8000 light years. 
Picture below has been shot with RGB filters - 40 minutes each one, and hydrogen alpha filter - 4 hours with 15 minutes subs. With Atik383 camera and TS130/910 0.79x refractor with reducer.
M29 open star cluster with hydrogen clouds and Milky Way stars

Clear skies!