lukebl

Thanks. The images are terrible!

Having thought I'd fixed everything. how wrong I was! Guiding is terrible. Something strange going on in DEC. Any ideas? Balance seems good and I can't detect any significant backlash. This is using an Off Axis Guider and a 1624mm Focal length.

Something which baffles me is that Starlink received 'permission' to launch all these things from the US Federal Communications Commission (FCC). What on earth gives them the right to grant such permissions which have a global impact, what are the criteria and how accountable are they? Seems a bit like me asking my District Council for permission to search for oil in the Antarctic.

Well, I'm chuffed to bits that, after dismantling the whole mount and reassembling it, it now appears to be functioning properly again and running smoothly. The original problem appears to have simply been a loose worm locking ring as suggested by Stuart1971 and others, exacerbated by me messing around with the grub screws and damaging some threads and generally being cack-handed. Now that I'm less intimidated by the interior mechanism of the mount, I'd be confident to undertake the Rowan mod on my other NEQ6 myself. It does appear to have been a creeping problem which I'd failed to notice, and explains a lot of the guiding issues I'd been having. In particular, it explains a curious satellite trail on this image which I posted a while back. I think it was simply caused by the RA drive rocking back and forth, and not by an oddly tumbling satellite. It would also clearly result in a lack of sharpness in long exposure images.

This is a capture with UV filter last night. No sign of the lovely cloud features visible a few weeks ago. This is it alongside an image from four weeks ago showing how it's rapidly getting bigger. Baader U-Venus filter, c. 20,000 frames. 3x Televue Barlow, Omegon RC8 and a ZWO ASI 290MM Mini Mono camera.

That's nice and sharp. I too will stick it out as long as possible to get the thinnest (and biggest) crescent. I find the most difficult thing is getting the damn thing in focus.

The seeing was fabulously steady here yesterday evening at about sunset, but despite that I could only catch the barest hint of clouds through the UV filter. Nice view though. Captured with Baader U-Venus and IR filters, c. 70,000 frames for UV channel. 8ms exposures. Green channel made from 50% UV and 50% IR . 3x Televue Barlow, Omegon RC8 and a ZWO ASI 290MM Mini Mono camera.

Thanks for the complement Pete, but I think your captures are superb and I think you can also tease a bit more detail out of them with a bit of a play in Photoshop. Last night I had an exceptional period of clarity and great seeing, so thought I'd capture some great detail. However, I'm processing the captures now and they seem to have almost no detail at all even though the images are sharp. I wonder if the solar lighting angle at the current phase makes the clouds less visible? The clouds were certainly clearer at half and gibbous phase, even though the disc was smaller.

No chance of any sharp captures of Venus here at the moment due to the seeing. But quite mesmerising to watch the beautiful shimmering crescent. Here's an animation of a few 12ms frames captured this evening through the Baader UV filter.. Omegon RC8, Atik 428ex, 3x barlow.

Here's a sequence of captures of Venus over the past two months. Recently, I've been disappointed at the lack of detail compared to a month ago, possibly due to the seeing deteriorating or maybe the vagaries of my own processing techniques are to blame. I've shown two versions here. The top one has the UV image in the red channel, and IR image in the blue channel. The bottom version is reversed. The convention seems to be for the top version, but as it's false colour anyway, I think I prefer the blue version. Omegon RC8, Televue 3x Barlow, Atik428ex, Baader UV and IF filters.

Ok I've stopped! Here's a video of the rattling. I've definitely made it worse, but not sure which action did it. Loosening and tightening the worm mesh nuts doesn't seem to make any difference at all. Fortunately I have another old (non-Rowan) NEQ6 I can use.

Thanks folks. I've done both things - checked the worm locking ring AND adjusted the worm mesh - and it's still rocking. In fact, something I've done has made it worse. The worm adjusting bolts are incredibly tight and have burred over a couple of my allen keys. Damn annoying!

Hi folks, I've had my NEQ6 for a few years, and I've had the Rowan Belt modification done. I can't say I've noticed this before, but the mount rocks noticeably back and forth in RA as this animation shows. Is this amount of play normal and can it be fixed? I'm not sure why I haven't noticed it before, but it could account for the vagaries of my guilding although I do ensure that the mount is balanced heavy on one side to compensate for backlash. However, I would assume that the Rowan Belt should reduce backlash?

Thanks folks. I haven't been posting any more recent Venus images, partly because the seeing seems to have deteriorated considerably since earlier in the month, and partly because of @CraigT82's awesome images putting mine to shame!

Thanks for the input gents. That's interesting as I already have an ERF from an incompleted PST mod with a TAL 100RS which I was never happy with. I'll have a go at rebuilding it, although I always liked the wider full-disc view that the the basic PST gives.

I got out my old Coronado PST today, even though the sun is very quiet, to test it out and I noticed that the view was incredibly faint. Too faint to see anything at all really. Could the ITF filter be the fault, as that seems to be the usual problem with PTSs? The pictures of rusty ITFs I've seen on the web show the filter looking very uneven at the periphery. However, mine looks fairly even right across as this photo shows. Perhaps the filter is so corroded that the corrosion has spread right across the filter? I haven't had it out for at least 18 months. Any ideas? I was thinking it wouldn't be worth fixing, but I've just checked the current price online, and maybe it's worth replacing the filter after all.

136108 Haumea is a Kuiper Belt object which was at opposition in Bootes last week, so I had a go at capturing it and measuring its light curve. My memory is terrible, as I've just noticed that I did the same thing a couple of years ago and posted it here on SGL but had completely forgotten. Here it is anyway. What's interesting is that it has an ellipsoid shape and rotates fast (4 hours). In fact it's one of the fastest rotating large objects in our solar system. It also has rings and two known moons. There was a bit of a controversy about its discovery by Caltech in 2004. A Spanish team got wind of the discovery before it was officially announced and speedily rummaged through some earlier images and pre-discovered it, and claimed it. They later admitted they had accessed the Caltech observation logs but denied any fraud, stating they were merely verifying whether they had discovered a new object. Yeah sure. Despite its vast distance, 49.5 Astronomical Units (Pluto is virtually nearby at just 34 AU distant), its movement was visible in this 3 hour stack of 4 minute exposures. Atik428ex, 200mm f/5 Newtonian. The bright star is mag 4.8 20 Bootis. Here's the light curve. Quite distinctive, with a range of about a third of a magnitude from about 17.1 to 17.4 over the evening. Here's its orbit and current position

Many thanks Andrew. Here's a somewhat better presentation of the light curve. I've averaged out every 10 measurements (i.e. 10 x 30 sec exposures) and inverted the scale so that it reads better. I have noticed that asteroids often have a dip or peak in mid-rotation, so a rotation period of about 3½ hours seems about right.

I've been watching the close approach of Asteroid (52768) 1998 OR2, and have captured an interesting light curve. It's a 2km Amor asteroid, which swings right out nearly as far as Jupiter and passes within 16 lunar distances of Earth on 29th April. It's normally pretty faint, but I measured it at around mag 13 last night and it's predicted to get to around 10.8 next week, although by then it'll only be visible for southern viewers. It was in Cancer last night, moving at around 8 arc seconds per minute and speeding up rapidly. I took 30 second exposures with an Atik428ex and 200mm f/5 Newtonian. Using Miniwin software, I generated this interesting varied light curve over a period of three hours, suggesting that it's quite irregular in shape. Wiki suggests that the rotation period is 3-4 hours, so I guess I've nearly captured a complete rotation. My measurement with Astrometrica indicated that its magnitude ranged from 12.7 at 20:40 to 13.1 at 23:00. Quite a significant range over a short time. Here's a composite image showing its position at 5 minute intervals: This is an image stacked on the asteroid using Astrometrica, showing its movement over 10 minutes This is a straightforward stack with DSS, of 199 exposures. No darks or flats. Finally, here's an animation of it at 5 minute intervals:

Sadly, I think that 99% of the public couldn't care less about the skies becoming more cluttered, and even embrace it. On my village community Facebook page (very busy with the lockdown), someone has excitedly posted updates on viewing them and loads of locals are out watching them. No interest in protecting our natural environment whatsoever, and we should consider the skies above our heads as an integral part of the wider natural environment.

No, unfortunately I can't see the secondary donut when looking down the tube for some reason. It's too dark down there! On the point regarding a subsequent star test, surely that would simply tell you whether or not you'd collimated it properly, but wouldn't help you regarding the cause? If it proved that the collimation was still out, you wouldn't be able to tell whether it was the focuser, secondary or the primary which was at fault and you're back to square one.

Many thanks @dweller25 and @Captain MagentaI think I may have resolved the issue by a circuitous route to the same process using all available tools. Here it is simplified: 1. Use Cheshire to align the focuser with the secondary donut by adjusting the focus tilt adjuster. (I use the Cheshire, as I can't see the laser spot on the secondary. This wouldn't be a problem with larger open-tube RCs, where you can directly see the surface of the secondary). 2. Use the Howie Glatter with concentric circle attachment to align the secondary with the primary, so that the laser circles are central and evenly spaced across the primary. 3. Adjust the primary so that the 'tunnel of mirrors' viewed when looking down the OTA is equal when viewing from the left, right, top and bottom (see pic below). Even a slight misalignment will be clearly visible as the 'tunnel' curves upwards, downwards, leftwards or rightwards if misaligned. 4. Repeat stage 1. Finished. I may be completely wrong, but it looks good so far.

Re-reading all the responses to my thread, and looking closely again at my particular scope, I've come to the conclusion that it's simply not possible to collimate it properly for one simple reason: The focuser is attached to the primary and moves with it. OK, you can align the focuser with the secondary, and then collimate the secondary. But as soon as you try and collimate the primary, the focuser moves with it and becomes misaligned with the secondary. Having a tilt adjuster doesn't help, as it's fixed to the same axis and moves with it. If you then try and realign the focuser with the secondary, then that puts the primary out again.

That Fullercope really is a planet-killer.

Actually, it's quite the reverse. The filter blocks everything except the UV. I bought mine a few years ago and have just seen how outrageously expensive they are now! Details here.