Another Hyperstar test. M81 and M82

[Daniel]

Took this last night, im still ironing out many problems with the hyperstar, mainly gradients im getting because of badly made flats, so you'll notice lots of strange gradients, also I took this right at the end of the night, when the clouds started sweeping in (not helped by the moon aswell)

Im currently working on building a lightbox which will make proper flats, although it's difficult making something that will not only cover the camera on the front, but also diffuse the light across the full 14 inches, im looking at making 2 diffusers between the lights and the camera.

Anyway, this is by far not an ideal object for a hyperstar since the field of view is way too big, but it was all I could point at that wasn't looking towards the moon which was washing everything out.

I haven't done much processing to it, because I know I could get a lot more if I sorted the light box out, but here it is anyway.


Daniel
:O)

[MarkS]

Daniel,

You don't need to make excuses - that's a good image for a moonlit night.

Have you got big screen HDTV?  Generate a white screen (e.g. plug a laptop into it) and point your scope at it from the other side of a a darkened room.  That will produce brilliant flats for general purpose use with your C14.

But background light pollution will always create gradients of it's own that need to be subtracted - even with filters.

How do you prevent frost on the corrector plate - a dew shield and dew heater?

Mark

[RobertM]

Daniel, that's a wonderful image by anyone's reckoning let alone a test!  If you go really deep with this one then you'll start to get all the intergalactic material appearing aswell.

[Rocket Pooch]

Daniel,

Point it at the sky in the day time with some diffuse plastic over the front, thats what I did with my 8" and it works fine and is simple to do.

Chris

[Daniel]

Thanks guys, I've just found these electroluminescent panels http://www.earlsmann.co.uk/ELPanels.htm whick Im going to use to make my definitive light box (my others consist of rolled up tubes with night lights at the end) though until then I shall probably use the point it at the sky method as long as I can stay awake that long.

Curiously enough this is a sample of the flat I get when I shine a torch at the tube through a couple of diffusers, i was worried about the bit at the bottom, so I called starizona and it turns out it's the flip mirror in the 40D and now I look at it it's got the same shape, they said it'll flat out ok though.



Makes me want to set up a lightbox manufacturing sideline, there's a gap in the market, every astro imager should have one, and yet there's no where you can actually buy one!

Daniel
:O)

[The Thing]

Lovely M81/82. I had a good look at them while in Normandy over Christmas and could see the dust lane across the middle of M82 (8" SCT 15mm 2" WA EP. Looks like you are starting to show the stuff that's jetting out of the black hole. http://chandra.harvard.edu/photo/2006/m82/ and http://chandra.harvard.edu/photo/2006/m82bh/. Keep the lovely images coming!

For flats I've started to use a white plastic lid from a 6 litre Wickes patching plaster container. It has very little embossed on it (which would all be well out of focus anyway) and covers my 8" SCT quite nicely. By taking several flats and rotating the lid between each I believe I am removing any effect the embossed words might have (is this right?). A bit of blank sky at zenith provides the lighting.

I am toying with the idea of adding lights into the tub of the container to provide a powered light box. An electroluminescent panel would be easier but a bit more costly than a plastic tub and a few LEDs. But you could just lay it on top of a vertical OTA. Of course if you only have a tiddly OTA...

[Fay]

Daniel how is it that the camera & cables etc do not get in the way of the Image?

[Daniel]

Fay, they do a little, hence the diffraction spikes, i can make out the exact shape of the camera when im defocussed while colimating. Fortunately it all goes away once it's focussed properly.

Daniel
:O)

[Fay]

Is your Celestron a 14" to accomodate the large camera?

[Daniel]

Hi Fay, yes it certainly helps, the secondary on the C14 is huge and nearly covers up the camera body anyway (though not completely)

Hopefully I'll be able to sort a lift out with enough room for DSC and bring it along.

Daniel
:O)