inFINNity Deck

Ok, that is interesting. The tilt can be checked by placing a Cheshire eyepiece in the focuser and brightly illuminate it while the lens-cap is on. If the lens-cell is tilted you will not see concentric reflections of the Cheshire's reflector. Nicolàs

Hi Dan, indeed it is quite curious why these artefacts are not point symmetrical. Did you check the front of the lens-cell to see of the are any small uneven spots along its circumference? Do you also see the artefacts in each and every sub? Nicolàs

Hi PottyMonster (is that your real name?), the effect you see could be an uneven spot along the edge of the aperture, although I would expect it to be symmetrical, which it is not in your case. The same for pinched optics, these should be symmetrical as well. The Tak FSQ85 indeed has these dark spikes, which are always oriented perpendicular to the centre of the image. Most likely cause is an unfortunate lens spacing in combination with the type of coating of the lenses and that they are the result of physical amplification and extinction of the light. More information on imaging artefacts in a white paper on my web-site: https://www.dehilster.info/astronomy/imaging_artefacts.php Nicolàs

If this photo is the pin in your focuser, then that is not the original one. The pin should be smooth, only having a smooth thinner section where the large balls run against. The original pins are made of hardened steel, not sure if the dowels you found are made of it as well. If not, they will be too soft. cheers, Nicolàs

Hi Giles, that cage should indeed be properly filled as otherwise the pressure of the ring-nut does not get properly and evenly distributed. And replace all balls, so that they all have the same size. Then when tightening do it in steps and test whether it holds enough load. When overtightened the central pin may get dented at which stage the focuser gets beyond repair (unless you can source another pin). Nicolàs

Hi Giles, see fig.3 on my webpage about my SkyWatcher Esprit 150ED: https://www.dehilster.info/astronomy/skywatcher_esprit_150ed.php The tiny balls, 18 in my FeatherTouch focuser, should fill the whole bearing. The purpose of the large balls is to create friction between the central thin pin and the conic outer bearing cage. This friction is created by tightening the large brass ring-nut, which pulls the three balls down in the conic cage, and to avoid that this causes too much friction between the gear housing and that nut a bearing with small balls is placed between them. As I wanted zero slippage I replaced the whole friction planetary gear by teethed planetary gear from a electro-motor gearbox (see above page). Nicolàs

Hi Andro, I have written software (FITSalize) to do sub arc-second level deformation measurements using a stationary scope and plate-solving. During development, based on the algorithms in J. Meeus, Astronomical Algorithms, (Richmond (VA), 2005), I tested my software against Stellarium and soon found out that Stellarium corrects for precession and nutation, but not for aberration (the phenomenon where celestial objects exhibit an apparent motion about their true positions based on the velocity of the observer). Precession and nutation are accurately corrected for, I could not find significant differences with my software. In order to be still able to compare the results with Stellarium I made the aberration optional. Nicolàs

Hi Alan, I just saw this thread last evening, so a bit late to chime in. I built my own dome six years ago of corten steel (base ring), pine (rafters), plywood (first layer of cladding), and zinc (final cladding), the construction of which can be found on my website: https://www.dehilster.info/astronomy/building-an-observatory.php Regarding your questions: Wind: it is a very good wind breaker, I have been imaging and observing quite often in conditions that seemed to be unfavourable. If you are going to build your own dome you need to avoid any openings larger than 10 millimetres that cannot be closed as the wind will blow in rain, hail and snow. Size: my dome has an inner diameter of 2.8 metres, which is fine when I am alone or only with my wife, but not suitable for more than four adults. I'd recommend a diameter of at least 3 metres (yes, 0.2m already makes a difference), but preferably at least 3.5 metres, that will easily accommodate around 8 adults. Move house: why, if you have an observatory? More seriously: you are moving to a new home and already considering selling it? In other words: do not live on fears! My wife and I hope to move from our current home with our feet forward first. In case future decides otherwise we probably have bigger concerns than an observatory on the roof of our house. A motor for controlling the dome azimuth is a must, for controlling the shutters is nice to have, but so far I am doing without and I have not missed it yet (for my azimuth-motor solution, see https://www.dehilster.info/astronomy/dome_automation.php). Main advantage of a dome is that you can do maintenance and test-runs while the weather is poor, most ROR domes do not allow for the mount to turn when closed. Domes also do have a downside: whilst very comfortable under windy/cold conditions, the capacity of a dome to provide this also results in what is called dome-seeing. Especially when doing solar (but at times also planetary) imaging the dome seeing can have a significant effect of the quality of the collected data. One way to overcome this, is to have the option to open a door or large window opposite or below the slit to allow a steady airflow (in our case the observatory is 7 metres above ground level and we can have all doors open, creating a chimney effect that brings cool air). Looking forward to your progress on this! Nicolàs

I use an ADC to get rid of the Newton rings. It has the added advantage that you can move the solar disc into the sweet-spot with it. Nicolàs

Those four bolts (six in my pier) are also referred to as a "rat-cage" (or "rat-box" as you called it yourself) of which is said that it would ruin the stability of your set-up. My rat-cage is very low, but friends of mine have 'decent' rat-cages and no issues at all. As long as the bolts are thick enough and the set-up properly balanced, the rat-cages are fine (IMHO that is). Nicolàs

Hi Vox24 (is that your real name?), both have some wisdom and truth in it. I am a hydrographic/land surveyor for 35 years now and know a fair bit about setting up all kinds of optical instruments on tripods, piers, etc. In addition I built my own domed observatory six years ago. Setting-up instruments on a level base is always easier than on a non-level base. But as mentioned, there is no need for the base to be level. In astronomy doing a polar alignment is easier on a level base simply because when the base is level the altitude of the mount does not change when the azimuth of the mount is changed. On a non-level base the altitude will change and as a result doing polar alignment may require a few more iterations in that case. So, for convenience, it is good to have the base level, but that is all there is to it. Nicolàs

Excellent work as always! Nicolàs

Nice to also see the Jovian moons that clearly in above image! Nicolàs

Yesterday I had another chance, this time it stayed long enough clear to shoot 20 x 15s subs in RGB and 60 x 15s luminance. Processing was thus now done with luminance instead of the blue channel as luminance. Capturing done between 19:35UTC and 20:08UTC with the SkyWatcher Esprit 80ED and ZWO ASI1600MM Pro Cool. Unguided tracking on the comet. P12/Pons-Brooks was at that time just south of Hamal in the constellation Aries at a distance of 241 million kilometres from Earth (1.611AU). The bright star in the end of its tail is HIP10657, the one at the left is HIP10795. Nicolàs

Here are two nice resources related to solar activity and sunspots: http://haso.unex.es/haso/index.php/on-line-archive/ https://svalgaard.leif.org/ A recent work that I would recommend is C. de Jager, S. Duhau, A.C.T. Nieuwenhuizen, Solar Magnetic Variability and Climate, (Alkmaar, 2020). Kees the Jager was a renowned Dutch solar astronomer and published this work when he was 99 years of age! Weather permitting I do sunspot observations daily both for a project led by Leif Svalgaard and for SILSO. My data is archived at HASO, hence above two links Nicolàs

Tonight had had another chance. Again weather was not quite cooperative. First I had to wait for the clouds to disappear, then, 10 minutes after imaging started, fog started to form. Luckily my observatory is 7 metres above ground level, so not too much issue there for the first five minutes, but it kept me from shooting luminance. Same processing as above. The bright star is Hamal. Nicolàs

Just found this thread. My last chance to image the comet was almost a week ago on the 24th around 19:43UTC: Imaging done in RGB using a SkyWatcher Esprit 80ED, ZWO EFW with ZWO RGB filters and ZWO ASI1600MM Pro Cool. Twenty subs of 15 seconds were collected per channel while a force 5-6Bft wind was pestering my set-up head-on, causing quite a few subs to be useless. Unguided tracking was done on the comet using a 10Micron GM3000HPS mount. Processing in APP both on the comet and on the stars, then recombined. Sadly enough clouds arrived at the moment I wanted to shoot luminance, so I decided to use the blue channel as luminance instead. Nicolàs

Hi Birman, I have written an ASCOM Generic UPS SafetyMonitor: https://www.dehilster.info/astronomy/ascom_generic_ups_driver.php Provided you use an UPS that uses the Windows logbook to log its status (for tested models see near the bottom of that page), the SafetyMonitor can trigger events in your imaging software such as parking mount and dome, warming up the camera. If the UPS is allowed to shut-down the PC a simple on-shutdown script can be used to shut down the mount (provided it ca be shut down using a command, see https://www.dehilster.info/astronomy/mountcmd.php). Nicolàs

Dear Matt, thanks for that link. It does not work in Firefox or Chrome, but the source of that page has all the required information, so thanks! The data was asked for by a researcher on the Rete newsgroups, apparently it will be used in an essay. Nicolàs

I am looking for an easy way to generate the path of the 23 December 447AD solar eclipse. This eclipse took place around Madeira and the Azores. I can 'see' the eclipse in Stellarium, but generating the path by changing time and the location is quite cumbersome and perhaps not very accurate, so I wondered if there is a tool that generates either the path in coordinates or even a map. Any suggestions are most appreciated. thanks in advance, Nicolàs

Compared to Autumn 2023 January 2024 was kind here in the Netherlands: 4 and a half clear nights, good for 47 hours of data (dates in the url are final processing dates, usually within a few days from start of capture): https://www.dehilster.info/astronomy/deep-sky-objects/C25_240110.jpg https://www.dehilster.info/astronomy/deep-sky-objects/M45_240111.jpg https://www.dehilster.info/astronomy/deep-sky-objects/NGC5906_240127.jpg https://www.dehilster.info/astronomy/deep-sky-objects/Sh2-261_240126.jpg Between 14 September 2023 and 7 January 2024: 0 clear nights..., so almost four months without a cloudless night. The forecast is rather poor: Hopefully the week after we get 7 clear nights... 😉 Nicolàs

Indeed, and if I am right, all lenses have positions independent of the focuser (i.e. not like a field flattener for an APO that moves with the focus-tube), so then there must be something wrong with the internal spacing or (one of?) the lenses... Nicolàs

IMHO the elongation is very consistent with wrong flattener to camera distance where the camera is too close to the flattener. Nicolàs

Any idea what that camera "revolver" is called and who produces them? Nicolàs

I image LRGB when the sun is below -15.5 degrees, and below -13.5 degrees when imaging narrow band. If I would do imaging at Espoo I would do so within the green lines in below graphs, the first for LRGB, the second for NB: So about 13.5 hours is indeed the max. These graphs are generated with my own script and can be personalised for your location and time-zone. It can be used stand-alone or embedded in a website. For a full description see: https://www.dehilster.info/astronomy/astronomical_twilight.php Nicolàs