12025 replies to this topic

[rolo]

Very cool!

[DMala]

Last night I set up the JSO 125x1200 mm SCT back on the mount and checked if the lower moonlight levels (compared to Aug. 29) made a difference in visibility of the Ring nebula M57. They did. The overall silhouette of the nebula showed a small but noticeable improvement in contrast resulting in a cleaner profile. In comparison to the previous night's observation with the 76.2 mmx1200mm Tasco 10 TE-5 refractor, I developed an impression of a very slightly better overall object visibility with the JSO, but with the JSO SCT the center hole of the nebula seemed to be even harder to notice. Being at the border between invisibility, averted vision fantasy and actual faint views, I would not consider such minimal differences between the two telescopes as definite.

 

It was an interesting comparison for me, because the JSO's objective diameter of 125 mm has a 49mm central obstruction. 125-49=76mm unobstructed, Vs the 76.2mm unobstructed lens of the Tasco 10 TE-5. So they have a similar focal length and similar unobstructed lens diameter, but different overall lens diameter and optical design. If I understand correctly the theoretical rules, excluding environmental, human, collimation, etc. factors, the JSO should provide somewhat higher resolution and the 10 TE-5 higher contrast, which I would expect to result in close overall performance on my chosen target. This is indeed the overall impression I got. And yes, also with the SCT I could not visualize M56  . Any tips besides using bigger telescopes?

 

BTW the JSO is so slightly off collimation based on the Fresnel rings at 120x, adding some degree of bias against it, but I doubt it would affect substantially the overall impression I got yesterday. 

[Terra Nova]

That must be a contrast issue, it looks like a perfect little smoke-ring in my FC76.

[Garyth64]

"It was an interesting comparison for me, because the JSO's objective diameter of 125 mm has a 49mm central obstruction. 125-49=76mm unobstructed, Vs the 76.2mm unobstructed lens of the Tasco 10 TE-5. So they have a similar focal length and similar unobstructed lens diameter, but different overall lens diameter and optical design."

 

 

I'm am sure subtracting the central obstruction from the diameter of objective is not right.  It just doesn't work that way. 

This was just discussed in another thread.

Edited by Garyth64, 06 September 2018 - 04:15 PM.

[DMala]

"It was an interesting comparison for me, because the JSO's objective diameter of 125 mm has a 49mm central obstruction. 125-49=76mm unobstructed, Vs the 76.2mm unobstructed lens of the Tasco 10 TE-5. So they have a similar focal length and similar unobstructed lens diameter, but different overall lens diameter and optical design."

 

 

I'm am sure subtracting the central obstruction from the diameter of objective is not right.  It just doesn't work that way. 

This was just discussed in another thread.

I read the recent discussion you probably refer to: my understanding is that subtracting the central obstruction is incorrect for calculating the max theoretical resolution power, but its does matter for estimating expected contrast. Am I wrong? 

Edited by DMala, 06 September 2018 - 05:19 PM.

[Garyth64]

Having a central obstruction can effect contrast. 

[steve t]

This is a Modulation Transfer Function for my 4" (102mm) Newtonian with a 35% central obstruction.  It was ran for me by another CNer.

What it shows, if I understand it correctly, is that for a low contrast images, like the center of the ring nebula or clouds of Jupiter, the scope should perform like a 66mm refractor.  For high contrast images like the moon or double stars it should perform more like a 102mm scope.

At the time I was restoring this scope I was worried that the 35% CO would be too large, but in actual use it doesn't seem to be a problem. 

 

Steve T 

 

Edit: On a moon less night, I find the ring's smoke ring shape easy to make out with this scope,  and sometimes can just intermittently glimpse the 13th magnitude star to the east, so with the JOS I'm surprised you would have any problems. I've read elsewhere that SCT optical alignment is critical?

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Edited by steve t, 06 September 2018 - 06:21 PM.

[DMala]

I think the biggest problem is being about 16 miles from Manhattan....

[clamchip]

I had 2-1/2 hrs to kill before my next job today up in Everett, too far away to come home.

So I observed my Cave catalog I have in my truck, went to the Everett Goodwill in search of

telescopes (found none) ate 4 Jack-in-the-Box tacos (these are so bad that I really like them) but

I did accomplish something of note, this particular catalog I would say is from 1957.

Here's a few quotes from within the pages:

"since the first launchings of artificial earth satellites" that's got to be 1957

"during the coming geophysical year 1957-58" and that's got to be 1957 too

Here is that catalog:

https://wiki.telesco...60s_Catalog.pdf

 

Robert 

[AllanDystrup]

.

     I've observed a garden sprinkler and an hour glass in Cygnus, and both had a black bow tie around the neck... They are both located not far from Sadr (gamma) in The Swan.

 

     These observations were done using mostly my C60/250mm Baader finder (with a classic design Zeiss C-lens), but also my "large" vintage Vixen FL80S/640mm refractor. On both scopes I used a Masuyama 2" 32mm eyepiece for magnifications of 8x and 34x, -- but I also employed an image intensifier behind the eyepiece to actually see and study these interesting objects.

 

 

     Here's the link to this observation: https://www.cloudyni...ield/?p=8818519; In the preceding posts I've described several more examples of what I've seen recently from my suburban backyard using my aging eyes and my old vintage scopes, -- but boosted with modern IIT  

 

 

-- Allan

Edited by AllanDystrup, 07 September 2018 - 03:14 AM.

[Garyth64]

I had 2-1/2 hrs to kill before my next job today up in Everett, too far away to come home.

So I observed my Cave catalog I have in my truck, went to the Everett Goodwill in search of

telescopes (found none) ate 4 Jack-in-the-Box tacos (these are so bad that I really like them) but

I did accomplish something of note, this particular catalog I would say is from 1957.

Here's a few quotes from within the pages:

"since the first launchings of artificial earth satellites" that's got to be 1957

"during the coming geophysical year 1957-58" and that's got to be 1957 too

Here is that catalog:

https://wiki.telesco...60s_Catalog.pdf

 

Robert 

With those old scopes you could see canals on Mars!

[DMala]

.(...)

     Here's the link to this observation: https://www.cloudyni...ield/?p=8818519; In the preceding posts I've described several more examples of what I've seen recently from my suburban backyard using my aging eyes and my old vintage scopes, -- but boosted with modern IIT  

-- Allan

Thanks, have you posted anywhere a very brief and general explanation of your image intensifying setup? thx

[clamchip]

With those old scopes you could see canals on Mars!

It would have been fun to have been an amateur back when we actually thought there were Martians

going about life just like us here on earth.

I've never seen the canals in the eyepiece, not even with 14 inches of aperture, but I have seen the canals

in photographs, even photos taken and posted by our friends here in the classic forum.

 

Robert

[Bomber Bob]

Hot in the City tonight!  [paging, Billy Idol]  Erratic seeing, of course, but my trusty Vixen FL80S made the most of it.  Had it out as the "pace scope" for my Vixen VMC200L.  I was sky testing this weird CAT, so many of the same objects as last time.  Lovely Saturn in the 8" scope was smaller & sharper in the 80mm fluorite -- no surprises there.

[AllanDystrup]

Thanks, have you posted anywhere a very brief and general explanation of your image intensifying setup? thx

DMala,

 

     Image Intensification Technology (IIT) using Night Vision Devices (NVD) is a relatively new branch of amateur astronomy, which started around 5 years ago in the US and picked up last fall here in Europe with a couple of guys in the UK.

 

     I entered the field in June this year, primarily because I wanted to supplement my rich field study of star forming regions (OB-associations) with viewing the molecular clouds and emission nebulae, that harbours these stellar nurseries. 

 

 

     We are breaking new ground here with this technology, so there's no consolidated references I can pass on to you, apart from the following articles on the first {edit: systematic and in depth observing} experiences with {edit: high performance gen 2+/3} NV in amateur astronomy:

• https://www.cloudyni...spectives-r3028
• https://www.cloudyni...otography-r3149

 

     Depending on whether you're located in the US (which, if I remember correct, you are) or in Europe, the recommendation for type of NV will vary. Also NV does best on fast scopes (small FL), which means that many classic telescopes are not that well suited.

 

     For those of us located in Europe we primarily use the setup described by Gavin Orpin (London, UK) in the article above, and detailed in these posts by alanjgreen (also in the UK) on SGL:

• https://stargazerslo...-little-better/
• https://stargazerslo...h-night-vision/
   

     The preferred US-setup is also described in the first two references.

 

     I'll end my comments on this subject here, as it is only tangentially of importance for the Classics forum (and some people will find it annoyingly irrelevant...). If after having read up on the subject (search for "Night Vision" on CN and SGL) you have specific questions, I advise you to post them in the EAA forum here at CN, where there are several pioneers in this field to help you out; (-- also of course feel free to PM me on the subject).

 

-- Allan

Edited by AllanDystrup, 08 September 2018 - 12:51 PM.

[Terra Nova]

I was introduced to this technology about 15 years ago in California when a friend demonstrated his Collins I3 Image Intensifier/Electronic Eyepiece. At the time, the setup cost around $2000 so I stuck with my lowly low-light security cameras adapted with a C to 1.25” nosepiece. Here is an early review of the Collins:

 

https://www.cloudyni...old-and-new-r33

 

It was also written up in Massey’s and Dobbin’s book on Video Astronomy that was published by S&T around that time.

[AllanDystrup]

I was introduced to this technology about 15 years ago in California when a friend demonstrated his Collins I3 Image Intensifier/Electronic Eyepiece….

    

     Yes, NV technology has in fact existed since the 1950'ies; I have such an early US single-stage Generation-0 M3 "Sniper scope" (photosensitivity: ~60 µA/Lm) from this era (but it is not in working order any more).

    

     I also have a 1960’ies “Starlight" NVD passive Generation-1 device (photosensitivity: 120 – 250 µA/Lm), which is OK for "terrestrial" viewing, but not of much use in astronomy.

    

     NV first really took off with the Micro Channel Plate (MCP) based Generation-2 technology in the 1970-80’ies (Photo-sensitivity >240 µA/Lm), and the last 5 years have brought out several brands of high performing, flexible Gen2+/Gen3 devices to the general (non military) market, with white phosphorus, auto-gating, adjustable gain and connectors to astronomy telescopes (C-mount focal) and eyepieces (TNVC afocal).

     

     So now we're starting to see some real observing reports using these devices with Ha narrowband and LP longpass filters.

    

-- Allan

 

PS: But I'm still using my R2 security cam for live video; these devices have different strengths & weaknesses (field of view, resolution, intensification, averaging etc. etc.). But we're moving into EAA territory now...

Edited by AllanDystrup, 08 September 2018 - 01:09 PM.

[Terra Nova]

     Yes, NV technology has in fact existed since the 1950'ies; I have such an early US single-stage Generation-0 M3 "Sniper scope" (photosensitivity: ~60 µA/Lm) from this era (but it is not in working order any more).

    

     I also have a 1960’ies “Starlight" NVD passive Generation-1 device (photosensitivity: 120 – 250 µA/Lm), which is OK for "terrestrial" viewing, but not of much use in astronomy.

    

     NV first really took off with the Micro Channel Plate (MCP) based Generation-2 technology in the 1970-80’ies (Photo-sensitivity >240 µA/Lm), and the last 5 years have brought out several brands of high performing, flexible Gen2+/Gen3 devices to the general (non military) market, with white phosphorus, auto-gating, adjustable gain and connectors to astronomy telescopes (C-mount focal) and eyepieces (TNVC afocal).

     

     So now we're starting to see some real observing reports using these devices with Ha narrowband and LP longpass filters.

    

-- Allan

 

PS: But I'm still using my R2 security cam for live video; these devices have different strengths & weaknesses (field of view, resolution, intensification, averaging etc. etc.). But we're moving into EAA territory now...

I still have my AVA Color Planetcam with a 1/4” CCD chip, my low-light Sony B&W with a 1/2” CCD chip, a little old X10 mini B&W with a CMOS chip which is great on the moon, and my most recent- a Samsung SB2000 color which is EPROM programmable and has onboard stacking which does a decent job on brighter DSOs. I have sold off three or four others, but I’ll keep these four as they offer a range of versatility.

 

I do think the Revolution Imager looks interesting. The thing I like about video is no computer is required, just a nice big LCD display and with a telescope on a tracking mount you can leave it unattended pretty much and have a real-time image. Great for a group of folks out on the deck.

Edited by terraclarke, 08 September 2018 - 01:15 PM.

[Paul Sweeney]

We had a really good night last night here in central Germany. While on the horizon Mars was in turmoil, straight up there was hardly a flicker. So out came the Viyen 80L. I started on Vega, and got to see the two 9.5 mag companions. That doesn't happen here very often. Mars showed a hint of a polar cap and some vague markings, but too much turbulence. Saturn was only a bit better, so I went back to the zenith. I started just after sunset, and suddenly it was 2 AM. Kinda dragging today! But it was one very rare night of excellent seeing, and I am glad I got to experience it.

[starman876]

raindrops are fascinating to look at. However I prefer snow

[member010719]

Last night I received the visit of my friend Tavi.

The sky was somewhat clear so we treated ourself with a bit of observations.

Using my 200mm F/6.16 Dobsonian at 164x with a vintage 7.5mm Celestron ''orange'' Plossl and a #23A red filter we started with Mars.

On Mars we saw very clearly the South polar cap.

Some grey markings were also visible on the disc of Barsoom.

The general aspect of the patches was that of the letter ''Z'' so I was suspecting we were looking at the meridian containing Syrtis Major.

Today , the ''Mars Profiler'' of Sky&Telescope'' confirmed that.

 

After seeing the Veil Nebula through UHC filter , but  very faint , we visited Neptun located to the East of Hydor / Lambda Aqr.

It had a very small ,grey-blue disc at 205x.

This is my first observation of Neptun for current year.

One should find first the linear asterism ''a'' to the East of Hydor.

Further East , there are two ''L'' shaped asterisms : ''b'' and ''c''.

Between ''b'' and ''c'' there is a isoscele triangle ''tr'' with the tip oriented toward ''b''.

Neptun is the tip of asterism ''tr''.

 

 

We visited some Deep Sky objects like M2 , M15, ''Saturn'' Planetary Nebula , M27, M56, M57, M71, NGC 6709 (Flying Sparkling Unicorn Cluster  !?   ) , IC 4756, NGC 6633.

As double stars , Pi Aql and Delta Cyg were the showpieces while 16 Vul (separation 0.85 '' ) was the example of a subarc double star.

This observations happened from my home ,from the city.

 

Ziridava

Edited by ziridava, 10 September 2018 - 02:08 PM.

[Karl Fabian]

Managed to get a so so image of Mars with the B&L 8001 a few days ago. This will be the first and only one for this apparition , not worth the effort. Maximum elevation here is only 23 degrees and the seeing sucks. On top of that had to image through an opening in tree branches that block my view South.. Have to set up the scope ahead of time in the proper spot to avoid the branches. There was no getting a perfect focus.....it was changing constantly in the seeing. Out of the mess 150 frames were stackable of 1500 with 80% quality cutoff. Mare Erythraeum on the Central Meridian. The image on right is from Mars Previewer II . Used an early version Celestron Neximage (re-packaged Toucam).20 frames per second with 2x barlow. The Windows XP laptop I use to make it work  is almost as old as the scope LOL..   

 

 

 

[Karl Fabian]

Dimmed the image a little.  I uploaded it from my old laptop an old laptop with a dim screen.

 

 

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[Bomber Bob]

The Swamp at 0300Z...

 

Temperature  83°F (28°C)

Heat Index 92°F (33°C)

Humidity 82%

Wind Speed W 7 mph
Dewpoint 77°F (25°C)

Seeing:  Schizophrenic, with big holes in low altitude clouds, a period of 100% clear skies, more clouds, fewer clouds, then 100% cloud cover.

 

Tiny TAK brings the smack on the Moon, Saturn, Mars, and DSOs.  My Swift 838 (50x700) delivered some big-time views tonight, beginning with the waxing crescent Moon right at sundown.  Bright in the gloaming at 35x (OR9), and very bright half an hour later.  At no time or magnification could I see fringing at the illuminated limb.  Lots of grays, and jet black shadows.  Best views at 117x with the OR6, and I forced it to go soft at 194x with the OR9 + GSO 2.5X Barlow.  When the skies were dark, I got the 3D Marble at 23x with the ER30.

 

Just past the meridian, Saturn was also in 3D with the RKE28 at 25x.  Titan was easy to spot, but with all the faint stars in the field, there were lots of other "moons" as well.  Disk & rings were crisp at 140x with the spectros PL5, and 2 grayish belts stood out.  Tried the Nagler 7 at 100x, but the spectros PL7.5 is a better eyepiece for this refractor.

 

Mars!  Barsoom was like blood red mixed with a bit of Tang.  I tracked it from just before to just past the meridian.  No canals, but with most of the dust settled, the moss of the dead sea bottoms marked a retreating Syrtis, and a near unbroken length from Acidalium to Argyre at 140x.  Pure white polar cap had a black thin hood.

 

I moved down to the flats SW of the shed, popped in the RKE28, and noticed that all the clouds were gone.  Within about a 15* radius of the zenith, skies were almost black, and the stars were twinkling.  At 25x & a wide field with no vignetting, this is a great sweeping eyepiece for my 838...

 

Vega in this scope is close in color to my Vixen 80 fluorite.  DSO seeing was 8/10, so I tried for M57.  Tiny Ring!  Barely got it with averted vision, but after my eyes adjusted, I could look directly at it.  The Coat Hanger is fantastic in the 838.  In my larger scopes, there are hosts of background stars, but centered in the Swift, there's a black band of space around it that really makes it rule the field.  M27 is a Dumbbell - two bright blobs with a short fainter connector.  Albireo is a tangerine versus a ghostly blue-gray pearl.  From it to Deneb there are crowded star fields full of real & optical doubles -- orange pairs seem to dominate the views.  M39 is sparse, and M29 is sparser -- if not for Sadr, it wouldn't be easy to find.  

 

My FL80S stayed in the shed.  With the Moon behind the skyline, I thought about bringing it out.  But Poseidon sneezed several times, and the stars all disappeared.  We're forecast to have better seeing tomorrow night, but at this point, with Florence drifting south, I'm glad I put in the time -- though I soaked two sweat rags.
 

[DMala]

Nice report Bob!