"Pattern matching" is a telescope pointing technique using Telrad which will land you on target from the first naked-eye alignment. Even if you are an inexperienced observer. Even if it's not obvious in the main EP. I'm using that technique exclusively for the past 5 years with my 12" Zhumell Dob right after I have made it possible in the DSO Planner as it allows to see over 100 deep sky objects per night near effortlessly, much more reliable GoTo, and allows to spend more time looking at the sky, than into charts/controllers.
The key app features supporting the "Pattern Matching" technique are:
- Works on a smartphone (important! as you need a truly single-handed device)
- USNO UCAC4 - you can be sure, that the stars you see in your up to 16" are charted.
- Adjustable Telrad pattern, so you can make it replicating the real thing you see over the sky precisely over the star chart.
- (optional) If you can't distinguish Pegasus from Ursa Major yet - digital compass mode, which allows to find the general direction of the target moving the phone around the sky in the stretched out hand (standard on most such apps, but in mine there is also a digital horizon mode, which is much more useful if you know your ways around and the directional line, so you know where to move and when to stop).
The technique is super simple:
- Tap the target object on the chart (or select from the observation list on the screen and open it in the chart).
- Turn on the Telrad overlay in the app's menu and make sure the real-time chart tracking is on.
- Hold the phone near the Telrad with one hand so you see two bulls-eye targets simultaneously.
- Push/pull the OTA with another hand until you see naked eye stars around the Telrad's bulls-eye exactly as on the chart (we all know how to do that from early childhood).
- Go to the low power eyepiece.
- Turn off the Telrad overlay in the app and turn on the eyepiece FOV overlay.
- Have the phone screen close to the eyepiece (I have a special cradle for the phone right on the OTA).
Having stars charted down to 16m around the object and the chart rotating for your EP view automatically (or manually if you prefer, as you can just rotate the phone) you can always easily match the pattern around the object's location in your EP comparing side-by-side with the chart (even like: one eye in the EP, another on the chart if in doubt, but with experience - not necessary).
Prerequisites for pin-point accuracy:
- you should see enough naked-eye stars (with experience, I need just one star visible close to the bulls-eye;
- the Telrad overlay in the app must be fine-tuned first to match your Telrad reticle between the stars. DSO Planner is the only star chart in existence which allows that and that's the key to success of the "Patterns Matching".