Observing with Street Lights

Observing with Street Lights
Dark sky sites not always necessary to see the Milky Way (This image was taken ouside of a B&B in Julian, CA)

Wednesday, September 7, 2016

Amateur finally finds Neptune; Check out the AIAA Space 2016 Conference; Sir Roger Penrose to speak at Chapman University; What to do with all your old paper tubes?

Greetings from Palmia Observatory

Well, this week has finally culminated in a successful finding of Neptune.  Or at least, I am relatively confident of that, even though one more rigorous test using the star chart overlay is needed to be completely sure.  Anyway before describing that picture and success story, we should check the calendar for upcoming special events.

First the AIAA Space 2016 Conference will be in Long Beach next week, September 13-16.  Check out the conference website for details if you are interested.  There will be
hundreds of speakers and exhibits.  One of our own science squad, Wants to Launch a Cubesat, Dr. Don, will be one of the speakers making a presentation there.  The conference is not free, but it is close by for those of us in OC, so check out:

https://www.aiaa-space.org/

The second event coming up on the calendar is a one day physics conference, this time it is free, at Chapman University on Wednesday, September 28.  News of this event were provided by Math Whiz, Dave.  Thank you Dave.  There is a 6-hour seminar on Holism and Causality in Physics, followed by a capstone lecture by Sir Roger Penrose.  He is certainly a giant and worldwide expert in the field.  He is known as something of a radical thinker and his talk is sure to exciting.  I just received his latest book from Amazon, who followed their well worn path to the observatory front door.  In this new book, "Fashion, Faith, and Fantasy in the New Physics of the Universe", which I'm just starting to read, he cautions us about the perils of getting too caught up in what is currently fashionable, and he will go over some of the issues that he finds are not quite yet supported by evidence in the three major fields of string theory, quantum mechanics and cosmology.  If the capstone speech follows along these lines, it should be very interesting.  Check out the details for the Chapman University events, free but you do need a ticket, at:

Ok, finally on to the search for Neptune.  What, you mean Neptune has already been found, even hundreds of years ago?  Ok, ok, I know, but finally, I was sufficiently bold to try to capture Neptune myself.  The first photo shows a 600mm telephoto, 30 second exposure, with text just below the suspected Neptune and a "+" sign at approximately frame center.


Image of Neptune taken with 600mm DSLR lens
How to find out if this is actually Neptune?

Neptune is a quite dim magnitude = 7.8 planet, so you are not going to see it with your naked eye, especially in city lights locations, so you have to mostly rely on your goto scope to point in the right direction.

Now last post I described my first attempt and failure at capturing Neptune.  The photo taken then was close to Neptune's position but too far off course to actually have Neptune in the camera frame.  And for several nights this week, I tried to fight the overcast clouds and get a good alignment just in time to point at Neptune and take a couple of shots.  But as you recall, my previous alignment was not close enough.  This week, I had two failed alignments and could not correct them before the clouds came in an blotted out my two brightest alignment stars, Arcturus and Antares.  I had one good alignment, I know because I checked out its repeatability with other just barely visible stars and the scope moved just right to place those stars in the center of the camera frame.  So, finally, it all came together and as a double check on the pointing accuracy, I uploaded the image to astrometry.net, thanks again to Author and OCA Secretary, Bob, so much for alerting me to this website service.  The results of that analysis are shown below:


Use astrometry.net to determine image location on celestial sphere
Use Astrometry.net to verify location of image on celestial sphere
Lets, check the astrometry analysis showed for the location in which the scope was pointing and where the star catalog says that Neptune should be found.  The coordinates for the frame center were found to be (RA, Dec) = (22 49 16, -8 38 16) and the catalog location for Neptune is (22 49 22, -8 26 31).  So after converting units of RA and Dec to arc minutes, the error is about 1 arc minute in RA and about 12 arc minutes in Dec.  This is ok since the photo frame itself is of dimension, 2.1 degrees by 1.46 degrees, so the target location is quite near the center of the frame, which is the goal after all.

So, my first step in finding where Neptune was, since I knew its location was indeed in the camera frame, was to look for objects about 12 arc minutes away from the frame center.  Based on this review, I tentatively identified the object in the previous photos as Neptune.  Now, with a 600mm lens, which in my case only has about a 90mm (3.5 inches) objective, so I'm not likely to see any detail, only a bright spot in the image, so, I used AIP4WIN to compare the relative brightness and sizes of close by objects.  See below:


Image of Neptune for comparison with brightness of nearby objects
Compare relative brightness of nearby objects

This image is shown 200% of the original and the suspected Neptune is the object on the right side of the screenshot.  It is bigger and brighter than the other objects, most not shown, and stars mostly show up as point sources, with some wiggle due to atmospheric seeing and mount wander.

So is it really Neptune.  Yes, I believe it is and my next steps in analysis, next week sometime, will be to overlay the star chart directly on top of the camera image and thereby directly identify the RA and Dec for that object and compare it with Neptune as the final indication, yes or no.

So, stay tuned!

Finally, I wanted to end with that great mystery of mysteries and that is What to do with all of those toilet paper tubes?  You know before too much longer all vendors will be going to "tubeless" delivery packages, so we don't have much time left to decide what to do.  Well, since I was having trouble visualizing  how the RA and Dec angles transform from one coordinate system to another, I thought having a model of the equatorial mount could prove very useful.  See below:


What you can make with carbboard toilet tubes for mathematical visualization
Cardboard Tube Model of Polar Mount Visualization Tool

The model is constructed so that the outer tubes just barely fit over the inner tubes, so the model can be rotated independently in both RA and Dec. Now, I can visualize the trigonometry just right.
By the way, if you are interested in purchasing this or similar models, I could be persuaded to consider an offer or two!



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