timwetherell

On 12/03/2024 at 10:10, RT65CB-SWL said:

They should have asked @timwetherell to design and build it...

 

Would have been fun! As it happens, I did once build a replacement for a historic telescope, the Oddie refractor that was destroyed in the Canberra bushfires back in 2005. The new one was a 9" f15 and whilst not a copy of the original, very much in that late 19th century style

Thanks for posting that - very interesting!  Did you find the image very flickery or sparkly (with the scintillation noise)? And how easy was it to order the EP here in the UK?

6 hours ago, lunator said:

Superb video

well done on getting the images.

cheers Ian

Thanks Ian

6 hours ago, The60mmKid said:

I think this is magical. Thank you for taking the time to make and share it.

Thank you

11 hours ago, Sunshine said:

Wow! I have never seen a time lapse of a variable done over such a long time. Your final product is impressively sharp, clean, and contrasty with nice dark backdrop and absolute pinpoint stars. Playing the video for the tenth time now I am blown away by the stark magnitude swing this star takes, going from almost invisible to the brightest in the field.

Thanks  Yes, it's a remarkable variation isn't it! I was lucky to get enough clear nights to complete it, England isn't known for it's lack of clouds

8 hours ago, markse68 said:

Excellent stuff Tim and I wondered what the kink in the brightening phase was- if it was due to missing periods of capture or something but the light curve Jeremy posted shows it clearly and it’s a common trait on longer period variables apparently-

https://www.aavso.org/sites/default/files//publications/staff_pubs/templeton_mira_humps_bumps.pdf

Mark

I think the slight kink is real as I didn't miss shooting for any long periods. Aim was once a week and sometimes it would be 10 or 11 days and sometimes 5 or 6 but overall fairly constant intervals. The other thing of course is that each frame had to be corrected for sky brightness (full moon, new moon etc. and some were necessarily at twilight) so there's a bit of jiggery there. I don't think it would have had much effect though as the brightness of the surrounding stars looks fairly constant.

49 minutes ago, jjohnson3803 said:

Looks like AAVSO is showing it over the hump:
 

Haven't done a pic for a few days but yes, that's broadly in line with what my photos have been showing - peak around mid May 

Cool thanks  yes S&T thought the peak was may 2nd but from my pics it looked more like the 10th or so. Wanted to do a visual drawing at max and min too, so I'd better get my skates on

4 hours ago, jjohnson3803 said:

You can generate a lightcurve of observations on the AAVSO site, but you have to enter Khi Cyg.

 

thanks  yes, it's awkward at the moment since it's only high near dawn. Couple of weeks in January when it's only visible low in the evening and low in the dawn were the worst for me. Not so good at getting up at 4am these days!

Had a look at the AAVSO site but couldn't see a curve for the current cycle. I'd be interested as it's been a bit hard to know when exactly the cycle is complete as some maxima are brighter than others

Recently finished a project to create a time-lapse movie of the variable star Chi Cygni. Period is about 407 days and the magnitude variation is spectacular ranging from about 4 to about 14. It's almost circumpolar to the UK so is visible at some point during any night. Amazingly given the British weather, was able to get a shot more or less every week. Would like to upload the video but it doesn't seem to work for some reason, but here's a link to it on Youtube

Would like to put it up here if possible. Tried Mov and AVI neither work. Does anyone have any suggestions for what formats do work on this site? 

1 hour ago, Vroobel said:

If the one in your avatar is made on your own, then I love it! It's most beauty cute house for the telescope! 😍

Thanks  yep, was built over several years and very useful. But I appreciate that for many people, this isn't a viable option. Only became possible for me in recent years. 

12 hours ago, Vroobel said:

Thanks

I didn't think about the clouds, when I was drawing sketches... The ATM/DIY keeps me busy all the time. I would die of boredom waiting for the clear sky. My mount was outside around 10 times in the 2022, including work on its improvement and tests. 😠 

 

Any possibility of an observatory at your place? Been a game changer for me

Love it! Very ingenious use of the scissor jack! Building your own stuff adds a whole extra dimension to the hobby - especially in a 99% cloudy country

Excellent!!

1 hour ago, skyhog said:

I managed to get out and watch this. The biggest issue was the wind. Big fork mounted sct users will know what I mean... 🙄

Actually was still as a mill pond down in the South West! We had a haze/light cloud all night but I often find that's accompanied by good seeing for planets

We were lucky to have clearish skies last night to see the double transit. Heavy haze but seeing moderately good. Really striking difference in the size of the two shadows! Sketch below at roughly 45 min intervals and dodgy photo from the end - single frame on DSLR. So happy that Jupiter is now getting higher in the sky for Northern hemisphere observers - last few years have been rubbish!

On 28/04/2022 at 13:46, HarryLP said:

My question is what should I/ do you see?

This is a sketch of what M3 looks like in my 7" scope in good seeing near zenith. 

13 minutes ago, beka said:

Hi timwetherell,

Very interesting. Could I ask the equipment you used? I am especially interested in how you did the 1𝜇m IR.

Best

Thanks  I have a infrared modified Sony A7s mounted on a skywatcher black diamond 90mm ED apo. Used a photographic  >950nm pass IR filter. The silicon CCD has some sensitivity out to about 1.1µm so it's recording in the 950nm-1100nm band. The filter is only 77mm diameter (bought it for a regular camera lens) so the 90mm refractor is actually a 77mm with that on the front. I find the Sony a really good astrophotography camera - really excellent CCD!

Got quite interested in Chi Cygni recently. Magnitude varies from about 3 to about 14 which is a crazy range. Apparently it's due to the surface temperature dropping which has the double effect of shifting the emission peak into the infrared and molecules forming in the cooler photosphere that absorb visible light. It's near minima so thought I'd try photographing it in visible and infrared light and sure enough, it's really bright at 1µm and really dim visually. 

You'll love it, southern sky has some wonderful objects. Spent 30 years down under and do miss the skies. Eta Carinae is one of my favourites. The main nebula is amazing but pay particular attention to the star at high mag. The two gas jets coming off are amazing, unlike anything else I've seen. Will be awesome in a big scope

5 hours ago, saac said:

That is really cool Tim; proper astronomy   

Jim

Thanks Jim

20 hours ago, markse68 said:

That's beautiful! Did you thread the end of the tube for the binocular objective? Did it have the eccentric collimation adjusters and if so what did you do with them? I've been thinking of doing this myself- would probably just use the bin ep as they are pretty decent really

Mark

Thanks Mark  Actually the objective housing is a snug push fit into the tube I had so wasn't any real need to thread - happily! I've made a few fine threads on my lathe but don't find them easy. If it were a loser fit I'd probably just have a grub screw to secure it. It is an the usual eccentric binocular cell but that only pushes it about 1mm off axis and for 7x magnification, I just didn't worry about it. 

Now have to think about mounting it somehow

19 minutes ago, Marvin Jenkins said:

Now all I have to do is get four consecutive clear nights😂

Yep, exactly!

Wanted to create a time lapse of a Cepheid variable star for a talk I'm giving and thought Polaris was probably the easiest target. This is 4 frames at 24 hour intervals covering its 4 day period. It only varies by about 1/4 magnitude but I think the pulsing came out quite well in the movie

Starting to enjoy a bit of astrophotography with my Sony A7s but need to correct the drive during long exposures. Autoguider is of course the easiest solution, but I kinda like doing things the old fashioned way. I'm probably the last man alive still using setting circles!  Anyway, trouble with manual guiding is that the thing you're photographing is almost never in exactly the same place as a decent guide star. Been thinking of all the ways to move the guide scope off axis, like classical three screw finder mount etc. Trouble is it's an 80mm guide scope so quite big and heavy and screws are very fiddly to use all the time. So decided it's probably easiest to move eyepiece instead. 

This is my home made rotate and slide stage that allows the eyepiece to be slid and locked anywhere over a 50mm image circle from the objective which amounts to about 5° of sky.  I've incorporated a 2x barlow into the guide eyepiece so it has an effective focal length of about 6mm equating to 100x. Of course a CCD doesn't need that but eyeballs kinda do to get a decent level of precision.

Still working on cosmetic improvements to the guidescope but the system seems to work well. now I need a clever solution to the problem of me leaving the guide illuminator on every time and wasting batteries. Current solution being to buy then in a 50 pack but that's not sustainable!