Recently Browsing 0 members
No registered users viewing this page.
Hi. Was up at dawn observing Mercury rising in the southeast and slowly swept my binoculars left. I was able to vaguely see a small triangle formed by Upsilon Ophiuchi, HR 6128 and HR 6137. That was the limit of view as sunlight was washing out anything else to the left of that. But I clicked on the adjacent HR6144 star in my Sky Guide app and it lists as being 6,900 light years away. When I checked the Ski Safari app, the same star is listed as 1,900 light years. I went online and found little info but, “In the Sky” web page it’s HR 6144 at 9 kilo years / 9,000 light years. Does anyone have any info as to why the huge discrepancies?
Thanks in advance for your help.
I am considering buying a Skywatcher al/az+eq mount to use in alt az mode for lunar CCD photography. I currently have a celestron 11 CDC and a celestron 8 on a nexstar evo mount. I can use both these telescopes with the celestron 'solar system align' and sharp cap for short (~10 sec 300-500 frame) captures. I want to replace the nexstar evo mount for the C8 with a sturdier Skywatcher AZ-EQ 5GT mount BUT -
1) the altz/az option is supposed to be 'for visual use'. Does this mean its tracking in lunar rate/alt-az mode is very poor ?
2) I am confused about 'alignment' (is this only necessary to accurately access the database of interesting object positions?) The skywatcher mount does not have solar system align - but it does have lunar rate tracking in alt-az mode. If I align on any random stars in lunar rate+alt-az mode with the moon centred in the telscope will the mount then track the moon? If not ,is there another way to track the moon ?
POLAR ALIGNMENT IF THE POLE STAR IS OBSTRUCTED (e.g. OBSERVING ON A S-FACING BALCONY!!!) Set up your scope on the floor (assuming it's reasonably level) in equatorial mode, with a rough guess at North. Put the tube into whatever 'home' position the instructions specify, or that you have chosen. Now choose an easily recognisable bright star at mid altitude. Pretend you HAVE polar aligned, and tell the scope to go to this star. When the slewing stops lift the scope very gently and turn the mount round till the star is in the centre of the field of view and you should have a fairly good polar alignment. If you are for example videoing planets and can also autoguide, this alignment may be all you need. But you can now refine it by the drift method if you need to - see https://www.skyandtelescope.com/astronomy-resources/accurate-polar-alignment/ This method should be quite useful for Southern hemisphere observing, where the 'south pole star' - Sigma Octantis - is difficult to find especially in light polluted skies. And of course my advice here applies if you have a North-facing balcony!
Well, I was finally able to put the newly repaired Sphinx through its paces over the weekend, Saturday night turned out a bit of a bust weather wise, however it gave me the advantage of already being set up for the following evening which was a completely different story.
Sunday...? Transparency not all that great, (perhaps NELM variable 3 to 5) and with a half moon shining, not ideal conditions for deep sky observing, however was still able to bag a few old favourites, including M53, M13, M92 and M51, M81 & 82. Then spent the next two hours exploring some galaxies in Canes Venatici, Coma And Virgo. Managed to pick up M63 - The Sunflower Galaxy, NGC 4565 - The Needle Galaxy, M64 - The Blackeye Galaxy, M104 - The Sombrero Galaxy, NGC 4631 - The Whale Galaxy, NGC 4559, M84 and M86 from Markarians Chain, The Leo Triplet and M87 - Virgo A, plus a whole host of other NGCs. Not much in the way of detail, (mainly due to variable conditions), they pretty much all lived up to their names as ‘faint fuzzies’, but nonetheless a most rewarding couple of hours. The Sphinx performed spectacularly, with each goto resulting in the target well within the FOV. The most gratifying aspect of the evening was the integration of the Avalon X-Guider into the ensemble, getting the main scope and finder dialled in is just so much easier now. Also the laser pointer performed its function perfectly as well, that being to improve efficiency of initial star alignment. All in all a most enjoyable two hours or so of observing.
Date: 2018 03 25 22:00 to 00:00
NELM: Variable 3 to 5
Seeing: II Antoniadi
Restrictions: 1/2 Moon to SW
Scope: C8 EdgeHD with modified longer focal length due to 2” Crayford and Diagonal.
FL: Approx 3200mm
Eyepiece: 22mm T4 Nagler:
Mag: 3200/22 = 145
AFOV: 82 Deg
Exit Pupil: 22/16 = 1.3mm