3rd August

The M51 supernova has not faded as much as I had expected.
Magnitude is now 14.11
This is a single 10 minute exposure.



While waiting for comet Garradd to move to a more favourable part of the sky,
I took 5x10 minutes of M57.
With previous attempts the guiding was not spot on, and there were problems with tube currents.
The 10" scope is performing better now, and the stars in this image are quite sharp and round.




  The Mira type variable star RX Lyrae near M57 has brightened considerably.
Compare this image with the ones at the end of August 2010.















  
     
The magnitude varies from 10.9 to 16.0 over a period of 247.82 days.
The magnitudes of the stars marked 'Ref' are known, and so the magnitude of the 'Object' star can be found.
The red line shows the calculated magnitude for each of the 5 frames.
The magnitude calculated for 3rd August is 12.28
     
     

Comet C/2009 P1 (Garradd)
This is the first attempt to set the ASA mount to 'comet tracking'.
It could hardly be easier. The comet drift in arcseconds per minute is entered for RA and DEC
and away you go.
This is 2x10 minutes. Clouds were beginning to be a problem, which is why the star trails appear
to have a few gaps.



Barry Morton also imaged Garradd last night, but a couple of hours earlier.
This animation shows how much the comet moved.

     


Satellite track

In one of the images of the comet I picked up an interesting satellite track.
The brightness varied (presumably due to tumbling) but did so unevenly.



I used the superb program CalSky to find out which satellite caused the trail.
CalSky soon identified the satellite as:
Intlst 5F11 Rocket, Dimensions: 8.6 m x 3 m, cylindrical, Brightness: 4.4 mag (at 1000 km, 50% illuminated) 0.8 mag (at perigee, full illumination),RCS: 19m2 (Radar cross section), USSPACECOM Nr: 15874 Internat. Designator: 1985-055B, Orbit: 269.4 x 27034 km, 7.84h, Inclination: 23.0°

Calsky can also produce a sky map showing the track as seen for your location..



The accuracy of this plot is stunning. My image was taken at 0:11:10, and was 60 seconds duration. Calsky produces time markers every 10 seconds.
Overlaying the Calsky map on my image produces a perfect alignment!



8th August

The M51 supernova magnitude is now 14.20
  This shows my values compared to many thousands from the AAVSO. Green points are for V filtered readings.

Clearly my colour camera without V filter introduces some error, but the overall shape of the curve is similar.
  Rx Lyrae is now magnitude 11.95,
a little brighter than on 3rd August.

Comet C/2009 P1 (Garradd)

60x1 minute. Stacked with DeepSkyStacker which can stack on the stars and the comet.



Stacked on the comet only - stars form trails.



Stacked on comet using kappa sigma clipping - stars almost disappear.



This movie shows 1 hour's movement of Comet Garradd. Sixty 1- minute frames were taken.

21st August


  The M51 supernova magnitude now appears to be 13.99
  This reading is unexpectedly high. My value deviates considerably from the AAVSO graph.


M27 the Dumbbell nebula is conveniently placed in the sky so I took 13x10 minutes.
Previous attempts did not have good guiding and were limited to 6 minute exposures.





31st August

Supernova 2011fe in M101 discovered on 24th August





I took 14x10 minute images.
The supernova magnitude appeared to increase throughout the observing period.
The average value was 10.98
The reference stars in this chart show more or less level brightness but the red line for the
supernova has a definite downward trend.



My value (red dot) agrees with those recorded by AAVSO