Search found 82 matches

by meteorB
Wed Dec 27, 2017 6:49 pm
Forum: Observing
Topic: Geminids 2017
Replies: 5
Views: 2869

Re: Geminids 2017

Hi, After a fairly disasterous Dec 2016 I decided to take myself to Tenerife this December for some winter sun and to observe the Geminids. I had 3 fully clear nights (12/13, 13/14 and 14/15) although the first and third nights were rather windy. Being at 2000m alt and despite the temp being just ab...
by meteorB
Sat Jul 09, 2016 1:19 am
Forum: Observing
Topic: Perseids 2016 DSLR imaging project.
Replies: 0
Views: 1390

Perseids 2016 DSLR imaging project.

Hi, A project for multi station meteor imaging using DSLR cameras has been developing between some observers from the NEMETODE group. This will involve setting up pairs of stations (or more than two if there are people in the right location) to take images of the same volume of sky during the 10/11,...
by meteorB
Tue May 24, 2016 11:54 pm
Forum: Gallery
Topic: The Sun 18th May
Replies: 18
Views: 4721

Re: The Sun 18th May

Hi Cliff, Thanks for the info. No worries, I was just being curious. As an opto-mechanical engineer I'm "in the trade" so to speak but you're spot on about manufacturers! Some of the claims made occasionally seem to stretch reality a touch. (especially filter claims!) I've been drooling over an H al...
by meteorB
Tue May 24, 2016 5:57 pm
Forum: Gallery
Topic: The Sun 18th May
Replies: 18
Views: 4721

Re: The Sun 18th May

Hi,
Thanks for the info. Are the etalons fixed or can they be tuned?
cheers,
Bill.
by meteorB
Tue May 24, 2016 8:18 am
Forum: Gallery
Topic: The Sun 18th May
Replies: 18
Views: 4721

Re: The Sun 18th May

Hi, Nice images indeed! I had a brief session in the early evening after work yesterday to try and have a look at limb darkening at a longer wavelength. This was succesful but the seeing was pretty awful. See the other post. Quite interesting how bland the solar disc looks like at 850nm. Although th...
by meteorB
Mon May 23, 2016 6:13 pm
Forum: Observing
Topic: Limb Darkening
Replies: 4
Views: 1927

Re: Limb Darkening

Hi, Phew, you had me worried for a moment :wink: I am pleased to report that whilst there is a tiny amout of vignetting it is MUCH less than the limb darkening effect. To save typing the location info, the image says it all. The numbers are the average of a box of 50 pixels square on the orginal sin...
by meteorB
Mon May 23, 2016 2:52 pm
Forum: Observing
Topic: Limb Darkening
Replies: 4
Views: 1927

Re: Limb Darkening

Hi, Vingetting is there on shots I've taken with a 22mm chip size on my refractor. However, I don't think there would be the degree, as measured if vignetting, in the centre 3mm or so of the image plane. Might be an interesting experiment to try it on blue sky as a flat field just to check. cheers, ...
by meteorB
Sun May 22, 2016 6:48 pm
Forum: Observing
Topic: Limb Darkening
Replies: 4
Views: 1927

Limb Darkening

Hi, When using the 390nm filter to observe the sun the limb darkening was very noticeable. This effect is often described in books but I thought I'd try and measure it. By using the IRIS software I simply drew a "slice" from the image centre to just past the edge. Yesterdays image gave this graph. 3...
by meteorB
Sun May 22, 2016 6:22 pm
Forum: Gallery
Topic: The Sun 18th May
Replies: 18
Views: 4721

Re: The Sun 18th May

Hi, The CN filter is nothing special, it just that the relatively wide bandpass overlapped the Ca lines gave me the idea. Despite a poor forecast this afternoon here has been gorgeous! Made a few more videos and got a couple of decent shots out of them. sunspot 20160522 1203ut y.jpg It's interesting...
by meteorB
Sat May 21, 2016 7:15 pm
Forum: Gallery
Topic: The Sun 18th May
Replies: 18
Views: 4721

Re: The Sun 18th May

Hi, This is another view from this afternoons brief session. 21/5/16. sun_160521_16-18-54-014_a.jpg Scope FL102 f8.9 refractor and Baader solar film filter. Camera: Image Source DMK21 and 390nm uv filter. Taken at 15.18UT Despite the problems I think the IS camera is a better quality piece of kit cf...
by meteorB
Sat May 21, 2016 4:31 pm
Forum: Gallery
Topic: The Sun (poor mans Ca II)
Replies: 7
Views: 2679

Re: The Sun (poor mans Ca II)

Despite a dire forescast (which has been mostly correct, sad to say) there was a break in the clouds a short while ago. :D Turned out to be a nice big sunspot... sunspot20160521_1547ut_a.jpg There are some unusual artifacts in the image when inspected closely. I'm not sure where it the hardware or s...
by meteorB
Fri May 20, 2016 12:56 pm
Forum: Gallery
Topic: The Sun (poor mans Ca II)
Replies: 7
Views: 2679

Re: The Sun (poor mans Ca II)

Hi, With the results of using my CN filter being better than I expected I've been doing some research and it turns out there is a whole world of solar observing at the CN wavelengths. Notably what seems to be know as the "CN band head" around 388.3nm. I say "around" because there are numerous CN lin...
by meteorB
Fri May 20, 2016 12:24 pm
Forum: Gallery
Topic: The Sun 18th May
Replies: 18
Views: 4721

Re: The Sun 18th May

That's a nice picture, I was hoping to have another look at it with the UV filter but I've got wall to wall cloud forecast for days on end here :-(
Maybe fortune will give me a break one evening after work...
It really is the classic sunspot!
by meteorB
Sun May 15, 2016 6:18 pm
Forum: Gallery
Topic: The Sun (poor mans Ca II)
Replies: 7
Views: 2679

Re: The Sun (poor mans Ca II)

Hi, Another sunny day! So I thought I'd try some more imaging with the UV filter. Showing gorgeous faculae and maybe even some super-granular structure. 20160515_1235ut_390nm_y_a.jpg (image is of w limb but rotated by 90 degrees.) ... and a nice spot just coming round the limb. 20160515_1258ut_390nm...
by meteorB
Sat May 14, 2016 1:16 pm
Forum: Gallery
Topic: The Sun (poor mans Ca II)
Replies: 7
Views: 2679

The Sun (poor mans Ca II)

Hi, After taking a few shots of the Mercury transit I'd forgotten how much fun solar observing was! Despite being a former acting solar section director decades ago I've not observed the sun for many moons , if you pardon the mixed metaphor... :wink: During the transit it occured to me that a filter...