1st & 2nd September 2011

M101 Supernova 2011fe

  On 1st September the sky was quite clear so more exposures could be made of M101.
I noticed that the Aug 31st images were overexposed and the supernova was saturating so exposures were reduced drastically to 100 seconds.
I also converted each image to mono with a 'boxcar' filter which should give better magnitude estimates.

On 2nd Sep cloud cover allowed only three exposures but this was enough for a magnitude measurement.
Aug 31 10.98
Sep 1 10.63
Sep 2 10.42

6th September

The M101 supernova continues to brighten. Exposures at 100 seconds were too long and were reduced to 60 and 70 seconds.
The magnitude was measured (average of 24 images) at 9.999, lets call it 10.0.

  2011fe is now the brightest supernova for nearly 20 years.

SN1993J reached magnitude 10, and 2011fe may get even brighter.
39 years ago SN 1972E reached mag 8.5.

2011fe is a type 1a supernova. These always have the same energy when they explode and so can be used to measure distance.

Galaxy M101 is only 20million light years away, hence the apparent brightness of the supernova.


8th September

Some clear spells in the early evening. 46 exposures taken of M101, all less than 60 seconds.
The measured magnitude of the supernova is 9.918
  Still brightening, but the peak must occur fairly soon.


13th September
  Bright Moon conditions. The Supernova in M101 was measured at magnitude 9.89 which is its brightest so far. AAVSO values seem to show that it has passed the maximum, contrary to my value.

14th September
  Supernova measured at magnitude 9.918

This is slightly dimmer than the preceeding night so it would appear that the maximum has been reached.

Bright Moon conditions made imaging faint objects impossible, hence another look at the Ring Nebula.
This is 22x5 minutes with re-focusing every 5 frames in an attempt to get the maximum detail possible.

The Mira variable RX Lyrae near M57 is near peak value.

  I dug out an image from Sept 2010 when it was near minimum, and plotted my values with AAVSO readings.

For some reason there is a large gap in CCD values.

18th September

M101 Supernova 2011fe

This is 2x10 minutes. Clouds prevented any more frames being taken.

  The supernova is showing a very gradual drop in brightness since the peak a few days ago.

The value recorded tonight was 10.098

It would appear that the combination of my colour camera and light pollution filter gives a magnitude reading a little higher than the true value.

  Adding 0.1 to all my readings gives a much better agreement with the AAVSO values.

I have also figured out how to turn the graph upside down!

22nd September

M101 Supernova 2011fe
  Sky conditions were appalling. Lots of cloud and even the gaps were filled with high level haze.

44x60 seconds were taken but only 4 frames were of any use.

The magnitude reading was 10.356


25th September

M101 Supernova 2011fe
  Sky conditions still appalling.
All images were shot through cloud.
The 29 best were used for finding the magnitude.

The magnitude reading was 10.613


26th September

Short break in the clouds.
Magnitude measured at 10.694

27th September

IC5070 Pelican nebula
8x 10 minutes
Only the top part of the Pelican fits in the frame.

Different processing

M101 Supernova 2011fe
  Sky conditions much improved!

The magnitude reading was 10.730


28th September

M27 Dumbbell Nebula

Another 17x10 minutes taken. Total now is 300minutes. A lot more background stars are showing up.

A central crop shows some of the wispy green stuff extending outwards from the nebula.

30th September

M27 Dumbbell Nebula

Total now is 600 minutes. I suspect that adding more data will not improve the image much.
The opalescent caste in the 28th September version is probably poor management of curves. I don't think the colours are realistic.
This is probably a better rendition.

  M101 supernova now at
magnitude 10.973