Nyctimene

If you don't mind reading some German: https://www.oculum-verlag.de/detailview?no=594 By the publisher of the Interstellarum Deep Sky Atlas - a very thought-out book, detailed and self-explaining, with Telrad circles. Moreover, a similar guide to the best NGC objects is on the way (Crowdfunding). The Big Binoscout is in print and will be available in November. Stephan

I really don't know - never saw it with my 8". Please check Phil Harrington's article linked above; there have been observers who spotted the Propeller with 6" scopes. The designated Dark Sky zone might help a bit. High magnification is needed. Give it a go, and let us know! Stephan

I've observed only 6207 (regularly when visiting M 13), but have never been able to spot IC 4617 up to now. Encouraging, that there are some "brighter" galaxies close by; I'll give it a try, perhaps next year, when Hercules is high positioned again! Stephan

I can make out the star trails/chains slightly "detached" quite well, but not as prominent as in Qualia's sketch. And, yes, these trails are "Herschel's hairs" - to quote his description (John Herschel, btw.): "hairy looking, curvilinear branches". Stephan

Never observed this with my two dobs, that have the secondary flocked (8" f/4 and 5.1" f/5). They rarely dew up, and definitely not starting at the secondary's edges. Stephan

Painting the secondary edge with a black felt tip or paint will still leave some reflexivity, esp. when light hits the mirror under grazing angles. I preferred to flock the secondary's edge (only half of it's circumference can be seen from the focuser) with self-adhesive velour flocking material (D-C-Fix here in Germany). Working in small pieces, I started with making a trapezoidal paper template for the part of the secondary, that points directly at the sky ( - the region of the major axis' exit) and cut it with fine scissors to the correct size and shape. I then transferred the template's outlines with a fine pencil on the velour's paper side, and cut out the part. A small pincette was used to put it into place. The same somewhat fiddly procedure followed with four more pieces (but you have to measure and cut only two templates, that are used back-to-front). The result is shown here with my Skywatcher Heritage 130 P Flextube: You don't have to work with extreme precision - the main point is just to get most of the stray light absorbed. Stephan

Some more ideas here: http://www.roelblog.nl/2019/09/summierian-ii-een-100mm-f-4-babydobson/#more-2809 Stephan

I'm using this observing hood: https://r-sky.org/en/products/observing-hood Not always, but in situations with light pollution (e.g. early in the evening - lots of cars and illuminated buildings), or, in contrast, when observing very faint DSO's. Works really well; only minor downside is the fogging up of eyepieces in winter times. You have to "ventilate" them for several seconds, and can go on with observing. Very good fabric and make quality, reasonable price. Stephan

Thank you, Pixies, for the vivid report, especially for the reminder concerning comet Churyumov-Gerasimenko. It seems to be positioned quite favourable in northern Taurus, and I'll revisit it, perhaps tomorrow morning. A fascinating thought, that Rosetta sent down the lander "Philae" to it's surface in 2014, and that this fridge-sized space probe is still there. According to the 2020 evaluation of it's two "bounces", the comet's surface ice is very soft and fluffy, softer than cappuccino froth or bath foam bubbles. Should be visible readily with the 12" (the comet, of course; neither Philae nor cappuccino ice...;-) )Stephan

It is strange, how the eye/brain team of a DSO's observer can be accustomed to view the faintest light structures on a dark sky background, and, in contrast to that, may have it's difficulties when it comes down to observe dark structures in brighter objects. When I went out this evening 20.00 CEST, the observing conditions were not great; NELM 5.0; SQM-L 20.6; together with a lot of light pollution (cars; two illuminated restaurants close by etc.), so I decided to point the 18" at M 13, without too much expectations. With 164x mag (Docter 12.5 mmf), several star lanes, known as "Herschel's hairs", mostly directed to N, were quite obvious. But up to now I have never been able to spot the dark lane structure known as the "propeller". This time, I spent, in analogy to some DSO sessions on faint objects, about 15 minutes to observe the cluster. Letting the eye wander again and again across the bright, widely resolved cluster, changing from direct to averted vision and back, slowly the dark "Y" pattern, resembling a "Mercedes" logo emerged in the S part of the cluster. One arm was pointing W, the two other ones to NNE and SE. The whole structure took up about 25% of the cluster's apparent diameter. I was not able to view it constantly - it "disappeared" several times, but returned, when I paused for a minute or had a look at the NGC 6207 galaxy close by. I guess, my brain will have stored the view now adequately, and it will be visible more readily the next time when I'm chasing it. A nice, appropriate sketch by Michael Vlasov: http://skyandtelescope.org/wp-content/uploads/Globular-M13-sketch-Michael-Vlasov.jpg An article by Phil Harrison about the propeller: https://www.cloudynights.com/articles/cat/column/phil-harrington-s/cosmic-challenge-m13s-propeller-r3106 Thanks for reading Stephan

A good choice. You don't have to be afraid of the RDF; it works quite well ( - the same one as with my 130 P Flextube). Perhaps you have to shim it a bit to get it aligned to the OTA. If the red LED is too bright (for DSO's), you can reduce it's brightness by putting a small piece of developed 35 mm film across the LED's exit to dim it adequately (works well with several RDF's in use with my dobs). Together with a wide field eyepiece, e.g. the 24 mmf/68° ES, or it's brother, the 26 mmf/62° LER, you will have enough TFoV (True Field of View) for star hopping. A lot of questions are answered in the huge thread about the smaller, but elder brother, the Skywatcher Heritage 130 P Flextube - the same scope; here under the brand name "AWB": www.cloudynights.com/topic/463109-onesky-newtonian-astronomers-without-borders/ Stephan

You could substitute the MDF base for this metal one: https://www.teleskop-express.de/shop/product_info.php/info/p5637_Orion-UK-Dobsonian-mount-for-300mm-aperture-Newtonian-Telescopes.html 13 kgs, so much lighter than a MDF base. Stephan

Counterweights seem to be a quite common enemy. In my case, it was a fixed one, attached to the massive equatorial mount of the 18" Newtonian, the Starkenburg-Sternwarte had been donated months before. In the observatory's completely dark dome, the counterweight was just at the appropriate height, when I went around the scope, to hit my left eyebrow - resulting in a pretty bleeding cut, that had to undergo a surgical treatment at midnight. Lesson learned - my 18" Dob has no counterweights. ( - But wheelbarrow handles, that stay fixed for convenience when I'm observing. I've learned to walk around the scope always at the front side, as you have to do, when approaching a horse.... all went well, up to now!) Stephan

Not so uncommon; the ICS owner is shown here with an accessory for the "Füssener Astrostuhl", allowing you to mount binoculars or small telescopes/spectives (I don't own - up to now; but Christmas is coming...): Stephan

To add: in any Newtonian scope (as your Heritage is), NORTH is 90° counterclockwise to WEST (so you don't have to move your scope). Just watch the stars (with a higher mag, to "accelerate" the movement), where they are leaving the field of view; right angled counterclockwise is N. Mnemonic: stars enter from the east, and wane in the west. Hth. Stephan

Posted April 3, 2020 My 8" f/4 Hofheim Instruments traveldob, here shown on the recently released equatorial platform, without the shroud, to show the construction details (and John L. Dobson's signature on one of the trusses!). Very compact, lightweight (8 kgs in toto), can be carried out of the shed in a single haul, Excellent optics, that hold collimation well, a smoothly operating Dob mount. At the moment, in a permanently setup situation - I hope, that one day I will be able to collapse it and to travel with it to view the southern skies. I guess, it will follow me some day into the nursing home....;-) Still valid up to this moment... Stephan

"Füssener Astrostuhl". Similar to the Geoptik Nadira, but with a much wider base (85x70 cm), so more security on uneven ground - doesn't topple over. I bought the "magnum" version for use with my 18", and I'm seated always safe and comfortable even at the highest position. Seat position can be adjusted in seconds without looking. Sturdy build; well balanced for moving. One of the best accessories I've ever bought. Have a look: https://www.intercon-spacetec.de/zubehoer/astronomie-zubehoer/stuehle/4888-ics-astro-stuhl-standard-grau-hoehe-90-cm-beobachterstuhl.html Stephan

Maybe the term "erect" refers to a single mirror diagonal, that will give you an erect image, but with reversed sides, as a mirror does. A nightmare, when you try to match such an image with a map (especially at 02.00 in the morning). What you need is a real RACI finder (right angle - correct image), as Johninderby says above, to get that naked-eye/binocular-like view you want to have. Usually it's a tad more pricey, due to the built-in Amici prism. No clue, why it's different with this store. Stephan

Happened to me twice the last nights, when observing the moon. First one was a lunar "snake", the Mare Anguis ("anguis" the Latin word for snake). One of the small lunar maria, located close to the NE border of Mare Crisium. With the 12", a really prominent dark (lava) area with an unmistakeable serpent shape. Needed a higher mag, and seemed to be prone to bad seeing. The second one, this morning, was the straight, black shadow (darker than lava albedo) of Valley Taurus-Littrow, directed roughly SSW-NNE. Landing place of the last Apollo (17) mission. (Will be close to the terminator this evening). Always something unexpected on the moon! Added a picture of Mare Anguis: Stephan

You'd better wait until Friday/Saturday night, when Triton (13.6 mag) will be in 16.2" (arc sec) distance of Neptun, almost the maximal elongation, which is 17". This evening it's just a tiny gap of 10" - even a good Maksutov will struggle with this. I spotted Triton three weeks ago with my 12" under 5 mag skies (after a suggestion by John), and it was not easy, needing averted vision. Phil Harrington ("Cosmic Challenges") rates the observation as difficult (3 of 4-rating) with large scopes (10" to 14" apertures). Perhaps it's better to wait a few days and to try, when the moon isn't up. Very high magnifications of 300x and more will be needed. A real challenge - but, give it a go, and let us know (the motto of the Deep Sky Forum members). Good luck! Stephan

Just came in from a planetary session with the 12" f/5 on the EQ platform. Thin haze, but rather good seeing, allowing 183x mag. Observed the last phase of Io's shadow transit. All four moons visible as tiny discs. Saturn showed the Cassini along almost the whole circumference; some faint bands on the surface; the planet's shadow on the ring could be seen clearly. Titan and Rhea readily visible, Dione was more difficult, but to spot with AV. Tethys (10.9), very close to the planet, was seen for fractions of a second. Japetus. No traces of Mimas or Enceladus. Rising moon made fainter stars fade out. Still one of the best views I had during the last two years. Stephan

Not all of them; the maps of French amateur Fréderic Tapissier (AVEX maps) seem to be based on such assumptions. The lightpollutionmap data are scientifically based. A link to the AVEX website (in French only, as it seems): https://www.avex-asso.org/

I can only comment on "lightpollutionmap", as it is the only map I'm using. It will give you a rough estimate of what can be expected, due to the "Up-Down" measuring method of the satellite (VIIRS). The satellite is "up" and looks "down" at artificial light sources, that contribute to the light pollution. But you, as an observer, are looking "up" and want to know about the amount of light that shines "down" on you. The satellite measurements don't give reliable infos about this. Only the use of a ground based photometer, that looks "up", e.g. the "SQM"-or "SQM-L" device, will help here. But you can get some information about SQM/SQM-L - measured data (mostly by amateurs, as I guess) from lightpollutionmap. Open the "toggle" menu, click on "feature" and select "SQM" and "SQM-L". The map now will show you differently coloured dots (corresponding with the sky brightness; check the legend), each of which can be clicked on for further information. You get a rather dispersed, but more realistic information about sky brightness, and can even enter your own SQM/SQM-L measurements to help other stargazers. Have a look, how the map shows the North York Moors National Park with this feature: https://www.lightpollutionmap.info/#zoom=7.76&lat=54.2583&lon=-0.9249&layers=B0FFFFFFTFFFFFTTFFF Hth. Stephan

Don't underestimate weight and bulk of a 10". The OTA weighs 19 kgs, the rockerbox 26kgs; the diameter of the rockerbox is 60 cm, and the height of the collapsed scope (in the rockerbox) 1 meter. For lunar and planetary observations, a smaller scope will do; and if you take that scope to a dark sky area, the views with it will be at least on par with a 10" under urban skies. Heather mentioned the Skywatcher Heritage 150 P Flextube, which is very compact and lightweight(7.5 kgs in toto), thus easy to transport to rural skies. I'm using it's smaller brother, the 130 P, and can fully recommend it. Btw., for the woodworker some plans for an equatorial platform: http://www.reinervogel.net/index_e.html Stephan

Your Skymax 127 is a compact scope, so the simple routine for my 80/400 FH Vixen frac should work quite well: Still outside, leave the scope assembled. Cover the eyepiece and the front aperture (Maksutov corrector) with the appropriate plastic covers. After that, put a large piece of moisture-absorbing cloth (a bath towel or similar; for my little frac, the R-Sky observing hood fits the bill quite nicely), and bring the whole stuff inside. Let it warm up slowly for the rest of the night. In the morning, take off the towel and the plastic covers of eyepiece and corrector plate, separate diagonal and eyepiece, and let it dry again for an hour, to remove any rests of moisture. Then you can store everything in the case; additionally, you can put a small pack of silicalgel inside to prevent moisture. Hth. Stephan