Eyes over the teapot!

As seen from the northern hemisphere, the constellation’s brighter stars form an easily recognizable asterism known as ‘the Teapot’. The stars δ Sgr (Kaus Media), ε Sgr (Kaus Australis), ζ Sgr (Ascella), and φ Sgr form the body of the pot; λ Sgr (Kaus Borealis) is the point of the lid; γ2 Sgr (Alnasl) is the tip of the spout; and σ Sgr (Nunki) and τ Sgr the handle. These same stars originally formed the bow and arrow of Sagittarius. (From Wikipedia, “Sagittarius constellation”)

In today’s “morning coffee” addition up at the observatory we turn our attention back to  early morning visual and binocular viewing! It’s 5:30 AM MDT. Spring has sprung and with it some of our old Milky Way friends in the South: the bright star clouds toward our galaxy’s center, the Lagoon nebula, Trifid, M22 globular cluster, M11 the Wild Duck cluster and others. However there was quite an unexpected surprise just above the constellation Sagittarius. 2 very bright objects, one red and one yellow nearly a fist width apart almost like 2 bright eyes! Yes, eyes over the teapot ,which is a known asterism for the constellation Sagittarius. The yellow object is Saturn. However the bright red object surprised me. This year, in fact by the end of this July, Mars will reach opposition and be nearly 2 times brighter than Jupiter! That hasn’t happened since 2003, when Mars was its closest to Earth in 60,000 years! Usually Mars is an inconspicuous rust colored dot lost amongst the stars. Not this year! It’s already making quite a show. Don’t miss it!

2 “eyes above the teapot” in early morning. Saturn is to the left and Mars right. Mars actually appears in the same binocular field as the Trifid nebula and the Lagoon nebula

Chile Dilly!

Recently I was browsing an online astronomy journal when I came across an advertisement for a remote imaging site in Chile: Chilescope.com. It was an attractive home page and of course being an avid astroimager I know about Chile, arguably the hottest property right now and home to all the latest and greatest ground based telescopes in the world. The Atacama Desert, driest place on Earth, could be the best observing site without actually being in outer space! Now I already own and operate a remote observatory in Mayhill NM, the birthplace of remote imaging so why would I be interested in anything else? Probably the main interest lies in the fact that I cannot observe the southern hemisphere’s sky from here! The fact that it is Chile adds a certain mystique to the whole picture. I decided to look into it further. The observing site is located in a remote part of Northern Chile. The nearest town is Ovalle, Chile which really isn’t that close to the Atacama Desert. It’s actually a good 700 km to the south.

X marks the spot where Chilescope is located. Atacama region is about 3 times the distance to the “Chile” label , north, on the map

Ok, perhaps I was a little disappointed, but after further research I discovered it still lies in an area in the North where the weather is superb and the climate is still quite dry. The site sits at a modest elevation of 5000 feet so quite a bit lower than anything in the Atacama region. The project was started by a group of astronomers in 2013 in collaboration with the University of Santiago.

Three observatories that were built are available for use. Two of them house identical telescopes and equipment, consisting of extremely fast (F3.6) ASA 20” Newtonians with direct drive mounts and FLI 16803 cameras.

Telescope 2 and 3 are 20″ ASA newtonians equipped with 4″ Wynne correctors for a corrected field of 50mm at an amazing F/3.6! An FLI Proline 16803 camera is used with a 10 position filter wheel. The mount is a direct drive equatorial mount which does not require meridian flip.

The third observatory houses a 1 meter RC scope! The site is directed toward amateur astronomers but also caters to professionals who are looking for quality telescope time. I am not generally familiar with “pay for play” telescope rental sites except for perhaps itelescope, which has, in my opinion, a very complex user interface and payment structure. This by contrast is extremely clean and simple. The cost for use of one of the Newtonians is 60 dollars per hour which is quite a bit cheaper than what I have seen for other sites. They provide the usual “Moon discounts” for imaging in moonlit skies. They also credit observers for mechanical problems and even bad frames. My estimate was that you could conceivably do a decent tricolor image project with the fast optics and discounts for perhaps around $400 or so.  I then looked at the calendar of availability expecting a long wait time but was surprised to see that I could start observing the next day! Of course the next thing to inspect was the images that were obtained by users. These were absolutely tremendous APOD quality images all the way! I was sold! A chance to image the famous Centaurus A galaxy and other renowned southern hemisphere gems! Luckily I had just sold some astroimaging equipment so I had some discretionary funds to test this out. My first target was of course Centaurus A! Payment is through PayPal either from your own account or via credit card. You have to register of course first and then your payment shows up as “chile points” where 1 point equals 1 US dollar.

The user interface is very simple and they walk you through everything.

The weather is recorded here as “unsuitable” but that is because it is during the day. You set up your times based on calendar availability. You have to check with your favorite planetarium program when your object will be visible. I use Stellarium, which actually has Ovalle, Chile in their database!  They do not image below 30 degrees so if your set up times are problematic either because of object visibility or conflicts with sunset or sunrise you will get an error message. Also of note is the late sunset time, around 9 oclock or so.

User planning page showing available observing time and overall image session

Remember it is Fall down there and they do not observe Daylight Savings! Currently you can easily image for 4-5 hours. They do reserve about 2 hours or so for non imaging functions. All of these details are explained both on the site and in a downloadable PDF . If you have any experience at all imaging the set up page is a snap. You enter the RA and Dec coordinates of your target, enter the number of subs you want to take, filter, binning, exposure time, how often you want to focus and even dithering. That’s it! When your session starts you get an email with a link to the session log which you can follow. At the end of your session your files are available for download. You can also download your bias, darks and flats at any time for free. They update their flats every week and darks every 2 weeks.

And now the results! This is a single 20 minute raw luminance image at 1:9 scale. The image analysis below shows the average FWHM is about 2.3 with this image scale (1 arc sec per pixel)  which is close to the lowest resolution I have seen here:

They tell you that their system is optimized for 20 minute exposures so that’s what I chose. On my first session there was a technical glitch and seeing was not good that night so I did get a 30% refund based on the number of frames I lost and/or had to throw out. Their customer service is outstanding. Emails regarding any issues are handled anywhere from within 1 hour to maybe a few hours but always resolved before the next imaging session. I checked all of my images in Pixinsight and my conclusion was that resolution in general was outstanding. On the best nights it was typical to obtain single 20 minute subs with an average FWHM in the 1 arc sec range. Less than great seeing was in the low 2’s. As mentioned the system is very fast and as a result is perhaps undersampling a bit with only a 1 arc sec per pixel image scale. The focal length of 1900mm (corrected) at F/3.6 demands precision focusing as the critical focus zone is a mere 20-30 or so microns! Consistent perfection in star quality is probably not realistic given this type of optical set up with the need both for absolutely perfect focusing with a minimal error margin, and field correction for a 20 inch Newtonian! As a result about 1/5 of the images I obtained had oval appearing stars in the very corners of the field at full resolution but I actually only had to discard a few that were frankly bad. The rest were acceptable to where I felt after processing would not be noticeable. The corrected field is 50mm so it is quite large considering the size of the optics! The other problem that came up was occasional failed plate solving which caused shifting of the target off center. These frames were credited back to me no questions asked. I was actually relieved to see that I am not the only remote observatory operator that has issues to deal with! The one variable there which seems to cause no trouble at all is the weather. I am into my second week of imaging and I still have not seen a single cloud on their all sky cam!

All sky cam near sunset.

All sky cam just before the start of imaging. The Milky Way is in full bloom! You can actually see Orion well to the north in the right upper quadrant. I believe that the Large Magellanic Cloud is visible in the south just to the right of center

In conclusion I would highly recommend this site for anyone who wants to image targets that can only be seen or optimally seen in the Southern Hemisphere. The cost is not prohibitive and the fast optical system makes it possible to obtain enough quality data in a reasonable time frame. The seeing at this site in Chile is excellent, and the resolution and image quality obtained make it well worth the expense, not to mention the excitement of seeing these amazing objects which we cannot see from Northern lattitudes! The user interface is very simple and customer service is superb. While you will have to throw out some subs like we all do at times, most of these will not come at additional cost. Best of all…they add 20% to your initial deposit if you are a Cloudy Nights online astronomy forum member!

Chile Dilly!

Thanks for reading!

Dr Dave

They blinded me….with Science!

Last month the first ever spectroscopy workshop was held in the US! It happened to be right across the street from my remote observatory at one of our good friends house. The first Sacramento Mountains Spectroscopy Bootcamp was hosted by Joe Daglen and Ken Hudson, 2 avid amateur spectroscopists. Now I do have a degree in astronomy so while I do have a passion for deep space imaging, it isn’t always about the nice pictures!

The amazing fact to realize is that most of what we know about the large scale structure of the universe, about how stars work, about how stars live and die and I would say most of the physical properties of the universe in general, is made possible by the analysis of light from distant objects using devices called spectrographs, similar to what you did in 3rd grade when you held up a prism in front of a light source and marveled at the colors of the spectrum. Spectroscopy is an extremely captivating facet of astronomy, very popular in Europe. Not so much here in the US…yet, but having meetings such as this will certainly go a long way toward getting more amateurs involved. The details are of course well beyond the scope of a single blog entry, but I invite you to read this introductory “primer” I wrote for Reflector Magazine 3 years ago.

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The first ever Sacramento Mountains Spectroscopy Workshop was a great success! An all star faculty made the trip up there including Francois Cochard, founder of Shelyak Instruments, the main amateur source of numerous spectrographs including the high resolution LhiresIII. There were a couple of professional astronomers and also an appearance by Stella Kafka, PhD, director of the American Association of Variable Star Observers. Currently the AAVSO is mostly involved with photometry but wants to become involved much more in spectroscopy and is assembling a variable star spectral data base. We had the opportunity to learn how to collect spectra using the high resolution spectrograph and how to process the spectral data. The astronomers who attended gave some fascinating talks on unusual stars, called Be (Type B spectral class with emission properties). These are stars that have orbiting shells of gas surrounding them that produce emission type spectra, rather than absorption (see the PDF primer above!). At any rate the meeting energized me to get my own equipment up and running here in Las Cruces (stay tuned for more on that!) We are all looking forward to SMSW-2 hopefully next year!

The first ever spectroscopy workshop in the US! That’s kind of a big deal I think!

 

The weather up here in the mountains is superb 300 days out of the year but not today! Fortunately we had a window of about 1/2 hour at night where we were able to collect spectral data

 

Outside the observatory at Joe Daglen’s in Mayhill NM which is right across the street from my observatory up there!

 

Inside the observatory participants can see the equipment used, which for spectroscopy is the scope on the right, a C14 on a Paramount ME

 

Here is the equipment mounted on the scope. The arrow at the bottom points to the spectrograph, a Lhires III. The camera labeled A is the one which records the spectra. The one labeled B is the guiding camera

 

Here we are! About 21 attendees and 4 faculty members. I am located under the white arrow 🙂

 

Well stay tuned for more spectroscopy coming up soon!

Thanks for reading!

Dr Dave

Seeing isn’t everything…it’s the only thing

One of the things a lot of people don’t realize is that you can have the most optically perfect telescope in the universe but chances are you will never realize that potential as long as you are Earthbound! Imagine lying at the bottom of a swimming pool looking toward the surface, let’s say 8-10 feet above you and trying to see the pattern on someone’s bathing suit who is floating on the surface of the water. Practically impossible unless there is literally no wave movement in the water between you and the swimmer! That is the quandry earthbound astronomers have to deal with, namely “astronomical seeing” Because we have an atmosphere above us which swirls and twirls with turbulence, jet streams etc , the result is twinkling and blurring of astronomical objects. This is why ground based observatories are located on mountain tops. Now “seeing” can be measured. When starlight travels through the atmosphere it goes from being a point of light to a disk of light. The larger the disc, the worse the seeing. The disc of light when plotted on a graph of width vs intensity has a shape shown in the diagram below. The astronomical measurement. The “full width at half maximum” of the optical intensity of the seeing disc is the most common measurement of astronomical seeing. This is the best angular resolution that can be achieved under your current conditions. Typically measured in arc seconds which is the standard angular unit in astronomy, the theoretically best possible seeing you can have on Earth is probably around 0.5 arc seconds and can only occur in places like Mauna Kea on the Big Island of Hawaii, the Atacama Desert in Chile and a few others. Here in Mayhill , New Mexico, we supposedly have really great seeing. I mean New Mexico Skies in all there promotional ads boasts of 1+ arc second seeing regularly. Since setting up my equipment here at Orion’s Belt which is literally a stone’s throw from New Mexico skies, I have been very curious about this. So far with my larger optical set-up I have not yet seen that amazing seeing they are claiming! Could it be that it really is better just across the street? Or maybe global warming has changed the climate here? Or maybe they are just full of it and perhaps it is not as good as they say. Or maybe my set up is not optimized to take advantage of the seeing. Maybe there is a tracking glitch or my mirror isn’t cooled down close enough to the ambient temperature or there is wobble in the pier or thermal effects from the observatory floor. So many variables to sort out it makes your head spin. That’s why I decided to resolve these questions by using a “seeing monitor”.
Seeing monitors have been around for as many years as professional observatories. Most professional observatories use the Differential Image Motion Monitor (DIMM) technique to measure seeing. This technique is implemented in hardware by using a two hole mask over an 8 to 11 inch Schmidt-Cassegrain telescope aperture, and measuring the root mean square (rms) fluctuation of the spacing of the two spots seen when a bright star is imaged a little bit out of focus with a fast camera. The reason two spots are measured is that the aggregate motion of the two spots due to poor tracking or wind vibration can therefore be rejected. However, the resulting system is complicated to automate, and invariably requires an automated enclosure to house the telescope as well, running the total cost up to many thousands of dollars. Amateur seeing monitors typically use a fixed single aperture system staring at Polaris, mounted on a heavy solid base. This way the wind motion and tracking error is gone. Polaris does move across the space of a measurement, so the linear drift of the centroid of Polaris’s position is determined and corrected. We call this the SIMM technique. Very smart people have developed software to interpret the data from these monitors and calculate the seeing. My set up employs a basic amateur ccd camera mounted on a metal base. This is a QHY 5L-II camera, a 1.2 Megapixel MT9M034 CMOS with exceptionally high (74%) QE and exceptionally low (~5e-) read noise. A 100MM F 3.5 is mounted onto the camera. Just to get a sense of where I was at with seeing vs what kind of imaging results I was getting I decided to mount the monitor on my AVX mount which I felt was stable enough for a test, plus I could more easily locate Polaris in the field of the camera. The Clear Sky Clock was forecasting average seeing conditions. Once I installed the camera and software, I started running the monitor over a period of several hours while at the same time continuing my current imaging project with the 16” scope. I was able to compare the results of my individual frames with the seeing recorded at the time the images were taken. The seeing results can be seen below. My images can be read by a program which can tell me the average full width half max values of the stars in the image. Basically what I discovered is that for that particular evening there was a range of seeing conditions which started actually pretty good, then declined and recovered a bit later. My images reflected almost exactly the changes in the seeing conditions and I was relieved to see that when the seeing was good, the image results were not far off from the local seeing conditions, maybe a half arc second on average. The imaging result is going to be affected by your system tracking, flexure of your optics etc so you have to expect a small degradation in the fwhm number. I would say 0.5 arc second above the local seeing is pretty good for a large amateur optical set up. Overall I would say the first test was a good one! I don’t think I have to sell everything and move or give up on my own set up. Not yet anyway!

This is the standard astronomical seeing measurement called “Full width at half maximum or FWHM” and is an angular measurement of the disc of the star at half the peak intensity

 

The “Seeing Monitor” is actually an astronomical ccd camera housed in a stable platform with a 100mm lens screwed on it.

 

Here is the monitor taped onto my AVX mount! It enabled me to point to Polaris fairly easily

 

And now the moment we have been waiting for! This is the seeing monitor live program which takes a series  of 0.01 sec exposures of Polaris, which you can see in the capture window, and over a series of exposures the seeing can be calculated. This is maybe slightly better than average suburban seeing which is by my experience 2.5 – 3 arc seconds

 

The seeing graph generated over the evening’s imaging session. The FWHM is in white. The blue is what is called “Polaris counts” which is a brightness reference and tells you how clear the visibility was based on the optimal value of 5. You can see the seeing was average at best but this was only one night of testing. More to come!

Thanks for reading!

Dr Dave

Omega Centauri

Perhaps like Edmund Halley in 1677, I “rediscovered” the largest globular cluster in our galaxy, totally randomly! It’s about 4:30 am. A frequent ritual up here in Mayhill NM, at the astronomer’s living quarters, base of Mintaka Hill, I go outdoors before sunrise to do some binocular viewing from the deck with my 16 x 70’s. Take advantage of the dark skies! So I’m sweeping around the sky and moving along the horizon to the south…Boom! What the heck is that? Looks like M13 on steroids! M13 known as the largest globular cluster seen from the Northern Hemisphere contains some 300,000 stars. Omega Centauri has 10,000,000!! I see that I am looking in Centaurus and I’m about 10 degrees above the horizon. Yep. That’s definitely the legendary Omega Centauri! Spotted for the first time in my life! A bunch of people in our neighborhood here have told me you can see it but it’s not easy. For most folks in the northern hemisphere it’s not visible due to sky glow in most areas and the fact it is skirting the horizon. Really a southern hemisphere target. I assumed you had to be higher up on the mountain here to catch it. I look with the naked eye to the South and definitely it’s blaring right at you at only magnitude 3 and change! A much easier target than I could have imagined. I am sure from the observatory it can be imaged especially since I am facing due South and have the drop down wall. Fortuitous planning on my part! But, before I image it I’m going to look through the refractor tomorrow. Can’t wait!

Screen shot from Stellarium looking due South. Omega Centauri is the “star” indicated by the white arrow. The group of brighter stars to immediate left make up the constellation Centaurus. Corvus is to the slight lower right of Spica. Scorpius is on the far left where Mars resides currently.

First light for the RiDK 16!”

At last, after months of gremlin battles we finally achieved first light for the RiDK 16″ scope! For details on the battle itself you can read the blow by blow in this page. This is a 10 minute guided luminance image of IC 5146, the “cocoon” nebula, a combination emission and dark nebula 4000 LY away in the constellation Cygnus. I picked this object mainly because there are a good number of stars and it is well positioned high in the sky at this time of year. Seeing was a marginal average and what I am discovering is that imaging at this focal length of 2800mm is not going to be easy. I am very satisfied with the star images. They are as advertised, crisp and round throughout the field and no flattener is required. OK so I guess you can get what you pay for sometimes!

“Cocoon” nebula. An emission/ reflection nebula in Cygnus. First light for RiDK!

Thanks for reading!

Dr Dave

 

Music and Stars

The Astronomical Society of Las Cruces has a rich tradition of education and public outreach. The club was founded by Clyde Tombaugh, discoverer of Pluto as many of you know. Many outreach activities have continued over the years. One of these is the monthly observing at Leasburg Dam State Park in Radium Springs, NM. Years before I became a member the Park Service and the ASLC got together to build an observatory at Leasburg. New Mexico State University donated a used Meade 16 inch scope and the club also installed a video system for the smaller William Optics 110 ED scope. Shortly after I arrived in New Mexico I joined the ASLC and became the observatory director. Every month we open the observatory to the public. This is a great opportunity for people of all ages to look through a large telescope. I think astronomy is a fantastic way to get people interested in science and this is important for all of us. Science encourages independent thinking, looking at things objectively and drawing conclusions from what you observe and not from what other people tell you. I think society is generally healthier as a result. I also enjoy the teaching aspect of it and seeing people’s amazement as they look at the rings of Saturn and other objects. Several folks don’t believe what they are seeing is real! It’s a welcome break from the self absorbing activities such as astroimaging. Trying to explain how the universe works to the general public forces you to understand it better!Einstein once said “If you can’t explain it to a 6 year old you don’t understand it yourself”

At any rate this last outing was one of the best I can remember. In the Summer , the night time astronomy is preceded by live music from a local performer. It’s a popular spot as the weather is very favorable this time of year. We get mostly campers that come by but some people visiting and local residents also enjoy the event. The Milky way was in full bloom at the start of the night. Actually reminded me of what I see up at Orion’s Belt Observatory in Mayhill! Usually it’s not that crisp. Radium Springs is way better than Las Cruces but still maybe a Bortle 4 sky. Seeing was fantastic. We started with Saturn and I was able to go to our 20mm eyepiece from the 30 which is rare for the 16″! The Cassini was sharp and the hemispheric markings were well resolved. Next was the Lagoon nebula followed by M13 where in the 16 you can reach in there and grab every star. We finished up with a journey to Andromeda. Low surface brightness even in the 16 but you can see the dust lane in the foreground. Bigger crowd than usual today! Hopefully I can go next month.

The parked Meade 16 and refractor just about to get going. The observatory is a roll off .

I think here we’re looking at Andromeda. The warm room is to the right and there is a laptop on a desk in the back that controls the scope

Thanks for reading!

Dr Dave