I want to find night sky objects with a GoTo mount. If you know me, I love technology. Yet for this hobby, I want to learn the night sky with as little support from technology. Huh? This makes no sense. Many astrophotographers use GoTo mounts to find night sky objects. Get with the technology Kevin! While I hear you, I still desire looking up into the sky and know what area of the sky I’m seeing. Anyway, this stuff costs money and most of us are not made of it so there.
How To Find Night Sky Objects: Star Hopping
I began my journey to find night sky objects by hopping stars. Most of us know the Big and/or Little Dipper or even the Orion Constellation. If you’re new to astronomy, learning the stars is not hard. I have a link on the home page of this site that has a printable sky map.
So how do I use a sky map to find night sky objects? First take some time to match the constellations on the map with what you see in the sky. You’ll quickly find that if you’re in the northern hemisphere, the southern hemisphere sky will not match. Once you match the sky you see to the sky map, pick an object. Then look for a path from the recognized area of the sky to the object you want to see. Simply connect the dots on the sky map then connect the dots in the sky the same way with your eyes.
Not every target you seek will be a dot in your sky. Light pollution varies depending on where you are and will mask some objects and others will look like smudges in the sky. Speaking of which, what is next when the object is not easily seen?
How To Find Night Sky Objects: Plate Solving
Ok so I found a way to use technology and still learn how to find night sky objects. This is M3 or Messier 3. I spent weeks star hopping between Arcturus and the Canes Venatici constellation. This globular cluster is a magnitute 6.2 or in other words, not very bright. The scale for night sky object brightness is backwards. The more negative the number, the brighter it is. The Moon when full is approximately a magnitude -12. The other frustration with M3 is that I live under Bortle Class 5 skies. With 0 being equal to dark skies, 5 means I have to navigate a fair amount of light pollution. Needless to say, there were a lot of frustrating photography sessions where M3 was not seen.
So I got inventive. Since I use APT (Astrophotography Tool) to capture my photos, I decided to give plate solving a try. The tool for plate solving looks like this.
First step for me is to star hop. I know my target and I know about where to look. I point my telescope there and take my first picture. Now this is where it gets interesting. I hit blind on the Point Craft window. The plate solving software opens in the background and is given the picture I just took. It analyzes this photo and determines the location in the sky the telescope is observing.
I then click on show when then sends the data to Stellarium. In Stellarium, I can see additional details regarding where the telescope is pointing. From this information I adjust my telescope and repeat. Once I have the object in view, I continue to adjust using my eyes.
Installing All Sky Plate Solver
This is how I found M3 after many frustrating weeks of searching the sky. It gets me into capturing photos quicker and I’ve later captured M101 using the same technique of star hop then plate solve. Give it a try with the software you use. Let’s discuss setting up the software.
All Sky Plate Solver is the software tool used with APT to perform blind plate solving. Since I don’t have a GoTo mount, this is my primary way to find night sky objects. Blind meaning the initial coordinates are not known. Start by clicking the settings button on the lower right corner of the point craft dialogue box.
In this box APT give you buttons to download ASPS (All Sky Plate Solver). Click that button and follow the instructions to download and install on your computer.
Setting Up ASPS
ASPS will perform plate solving with the addition of indexes. On first start up it will ask you to install the indexes. The information you need to complete this task are telescope focal length and camera chip data.
Do this for all of your telescopes and cameras. This will avoid having to download them during a session.
Now the tricky part, is the focal length. If the calculated focal length on your picture is not close to the telescope manufacture’s number, then it will take a long time to solve or not solve at all. ASPS in version 188.8.131.52 has added a Settings Assistant. Use it. As you can see above, the focal length is 1741. This is the calculated value for my Meade ETX-125 which is a 1900 mm focal length telescope.
Once you follow the directions and acquire the focal length, enter that same number into APT. APT sends that info along with the picture to ASPS to plate solve. This way the solving time is short and you don’t get errors.
I have not figured out why there is such a large difference in focal length for this telescope. Once I do I’ll update this post.
How To Find Night Sky Objects: GoTo Mount
Like I said, I don’t own a GoTo Mount, but I do have access to a fully robotic telescope. I recently used it to capture the Great Globular Cluster in Herucles or M13 or Messier 13. It contains approximately 300,000 stars. In comparison M3 contains approximately 500,000. So on my rainy days I use this telescope to capture photos and add to my post processing fun. This photo is in mono or black and white. I plan to take a color photo with my telescope and non GoTo mount. Look for it in the near future.
Globular star cluster simply means a ball of stars. There are open clusters which take on irregular shapes, but are close group of stars. The Pleiades or 7 Sisters is an open star cluster shown here. From where I live, I can see a great many night sky objects and photograph many more than what my eyes can see.
I do however want to address those of you living in the heart of a big city. Get a GoTo mount for your astrophotography. The light pollution there is blinding, but many astrophotographers are able to get stunning photos of night sky objects from their apartment balcony for example. The other option is to travel away from the city. Then you can see the stars and learn to star hop your way around.
Let me know what your experience is in the comments below. Thanks and clear skies!