Guide Log Interpretation

cpatel823

I have a Rainbow Astro RST-135 mount and am using the Redcat 51 for imaging, ASIAIR PRO, EAF, and the ASI1600MM Pro for the main camera and the ASI290MM Mini as the guide camera. My guide scope is a SBIG eFinder lens and Borg Helical focuser giving me a 100mm (rough) focal length. I did my first round image captures just about 2 weeks ago and got some good first images without guiding using 2 minute exposures. I just ventured into guiding this last weekend with 5 minute exposures so I want to understand what I am seeing in the Auto guide Log and how to properly read it and am wanting to understand. Is there any available information on how to properly read it? I did not touch any of the settings, I just calibrated and off I went. I watched the graph a little but did not record what the error was at the end. My sessions ended when I must have snagged a cable, and the image just showed streaks like straight star trails. The second time I had clouds move in and must have lost the guide star and got another frame of straight diagonal streaks.

I uploaded the log, and am looking to understand what the sequence of numbers mean? I can import into excel graph the data, most likely comma delimited but since there are no headings I cannot figure out what happened! Some might say if the pics look good ignore the rest but I tend to want to understand what the data says. Any help appreciated, hopefully someone knows how to read the data after the fact. Thank you - Chris

phd2-guidelog-2021-02-05-205640.txt

8kB

w7ay

cpatel823 am looking to understand what the sequence of numbers mean?

https://openphdguiding.org/phd2-log-viewer/

Unfortunately this forum does not allow other users to download the file that you posted.

Chen

cpatel823

Sorry about that, her is a cut of the log, I am interested in understanding what the number sequence relates to after the Settling is complete, I am assuming time, and movement but not sure how to read into direction, axis, and the like. Thank you - Chris

Guiding Begins at 2021-02-05 21:01:15
Dither = both axes, Dither scale = 1.000, Image noise reduction = none, Guide-frame time lapse = 0, Server enabled
Pixel scale = 5.98 arc-sec/px, Binning = 1, Focal length = 100 mm
Search region = 50 px, Star mass tolerance = 50.0%
Equipment Profile =
Camera = ZWO ASI290MM Mini, gain = 110, full size = 1936 x 1096, no dark, no defect map, pixel size = unspecified
Exposure = 3000 ms
Mount = RainbowAstro RST/MC700GE-II, connected, guiding enabled, xAngle = -86.8, xRate = 0.462, yAngle = 177.8, yRate = 1.159, parity = +/-,
X guide algorithm = Hysteresis, Hysteresis = 0.100, Aggression = 0.700, Minimum move = 0.200
Y guide algorithm = Resist Switch, Minimum move = 0.200 Aggression = 100% FastSwitch = enabled
Backlash comp = disabled, pulse = 0 ms
Calibration step = phdlab_placeholder, Max RA duration = 2000, Max DEC duration = 2000, DEC guide mode = Auto
RA Guide Speed = Unknown, Dec Guide Speed = Unknown, Cal Dec = 68.8, Last Cal Issue = None, Timestamp = Unknown
Dec = 68.8 deg, Hour angle = -3.93 hr, Pier side = Unknown, Rotator pos = N/A
Lock position = 1605.882, 657.093, Star position = 1605.937, 656.603, HFD = 3.83 px
Frame,Time,mount,dx,dy,RARawDistance,DECRawDistance,RAGuideDistance,DECGuideDistance,RADuration,RADirection,DECDuration,DECDirection,XStep,YStep,StarMass,SNR,ErrorCode
INFO: SETTLING STATE CHANGE, Settling started
1,4.749,"Mount",1.017,-0.498,0.555,-0.930,0.350,-0.930,757,W,802,N,,,2142,32.60,0
2,7.305,"Mount",0.631,-0.254,0.289,-0.585,0.207,-0.585,448,W,505,N,,,2140,32.54,0
3,9.583,"Mount",-0.256,-0.071,0.057,0.264,0.000,0.000,0,,0,,,,2210,33.08,0
4,12.863,"Mount",-0.489,-0.094,0.066,0.498,0.000,0.000,0,,0,,,,2229,33.27,0
5,16.114,"Mount",-0.555,-0.128,0.096,0.568,0.000,0.000,0,,0,,,,2152,32.67,0
6,19.346,"Mount",-0.578,-0.095,0.062,0.586,0.000,0.000,0,,0,,,,2094,32.23,0
7,23.174,"Mount",-0.649,-0.226,0.189,0.675,0.000,0.675,0,,583,S,,,1990,31.39,0
8,26.364,"Mount",-0.294,-0.218,0.201,0.324,0.126,0.324,274,W,279,S,,,2124,32.45,0
9,29.025,"Mount",0.032,-0.116,0.118,-0.014,0.000,0.000,0,,0,,,,1886,30.58,0
10,32.305,"Mount",0.123,0.007,0.000,-0.122,0.000,0.000,0,,0,,,,1981,31.30,0
11,35.479,"Mount",-0.051,-0.039,0.036,0.056,0.000,0.000,0,,0,,,,2003,31.54,0
INFO: SETTLING STATE CHANGE, Settling complete
12,38.645,"Mount",0.010,-0.088,0.088,0.004,0.000,0.000,0,,0,,,,2012,31.59,0
13,41.902,"Mount",-0.050,-0.140,0.137,0.071,0.000,0.000,0,,0,,,,1959,31.14,0
14,45.116,"Mount",-0.153,-0.201,0.192,0.182,0.000,0.000,0,,0,,,,1836,30.13,0
15,48.969,"Mount",-0.276,-0.238,0.222,0.309,0.140,0.309,303,W,266,S,,,2170,32.78,0
16,51.855,"Mount",-0.208,-0.091,0.079,0.220,0.000,0.220,0,,189,S,,,1964,31.18,0
17,54.875,"Mount",0.035,-0.037,0.039,-0.029,0.000,0.000,0,,0,,,,1947,31.03,0
18,58.100,"Mount",0.195,-0.022,0.033,-0.190,0.000,0.000,0,,0,,,,1960,31.14,0
19,61.269,"Mount",0.114,-0.037,0.043,-0.107,0.000,0.000,0,,0,,,,1911,30.73,0
20,64.500,"Mount",0.066,-0.017,0.021,-0.063,0.000,0.000,0,,0,,,,1960,31.16,0
21,67.719,"Mount",-0.038,-0.183,0.180,0.065,0.000,0.000,0,,0,,,,1997,31.49,0
22,70.993,"Mount",-0.089,-0.110,0.104,0.105,0.000,0.000,0,,0,,,,1955,31.15,0
23,74.239,"Mount",-0.174,-0.087,0.077,0.186,0.000,0.000,0,,0,,,,2001,31.52,0
24,77.463,"Mount",-0.204,0.040,-0.051,0.196,0.000,0.000,0,,0,,,,1913,30.77,0
25,80.718,"Mount",-0.207,0.077,-0.089,0.193,0.000,0.000,0,,0,,,,1958,31.11,0
26,84.144,"Mount",-0.259,0.100,-0.114,0.241,0.000,0.241,0,,207,S,,,2076,32.05,0
27,87.108,"Mount",-0.111,0.161,-0.167,0.086,0.000,0.000,0,,0,,,,2158,32.73,0
28,90.376,"Mount",-0.148,0.186,-0.194,0.119,0.000,0.000,0,,0,,,,2081,32.11,0
29,93.641,"Mount",-0.082,0.154,-0.158,0.058,0.000,0.000,0,,0,,,,2175,32.87,0
30,97.337,"Mount",-0.270,0.194,-0.209,0.237,-0.132,0.237,285,E,205,S,,,2111,32.33,0

Tech@ZWO

cpatel823

hello，You can drag log to PHD2 log viewer

w7ay

cpatel823

First thing first... because of the very large periodic error (70 arc seconds peak-to-peak or worse) of the RST-135, and a period of 430.82 seconds from its strain wave gears, the rate of change at two regions in the 430 second period can be too large for a 3 second exposure time to keep the mount in track. Most RST-135 users settle with 0.5 second exposure time (hence sampling period of 0.5 seconds for the feedback loop). When seeing is really poor, back off to 1 second. 2 seconds or more of exposure time is invariably worse with the RST-135.

As suggested by ZWO in their answer to you, run the PHD2 Log Viewer and use the file menu to open your log file, where you can then view the log carefully.

With a 3 second sampling that I notice you are using, I suspect the tracking error could be as poor as 2 or 3 arc seconds. Whether that is acceptable depends on the plate scale of your instrument.

That being said, I used to typically get about 0.5" to 0.7" RMS total error during the ASIAIR v1.3 time frame with my RST-135. Ever since v1.5 (it could have even been the v1.4 transition; I don't remember now), the error has more than doubled. There is some severe autoguiding bug that others with various mounts are also seeing.

Next, notice the time stamps in your log. You had set the exposure to 3 seconds, so the second column of the log should increment by precisely 3 seconds per row of data. Notice that it jumps around significantly and slowly lagging. From row 12 (time stamp 38.645 seconds) and row 22 (time stamp 70.993 seconds), 30 seconds should have elapsed. However, the difference in time stamp that we see is instead over 32 seconds. The guide camera frames appears to be slipping slowly at the rate of some 10%. This again appears to be a bug -- the guide camera's FPS is simply not keeping up.

ZWO has not publicly admitted to any guiding bug, but you can read numerous reports from users of run-away tracking on this forum, and also on the ASIAIR Facebook page. Most, like myself, are reporting that tracking used to work on ASIAIR and it no longer works (in my case, severely deteriorated).

I have not seen a complete run-away with my RST-135 that many are seeing with various other mounts. Just that the error has more than double from late 2019 version of the ASIAIR. However, I was just in a discussion on this forum with someone with an iOptron mount that has a complete run-away tracking problem. I suspect ZWO is not running any regression testing from one release to another, otherwise they would have caught the problem before releasing the software to users.

Fortunately, I can tolerate the error that I am seeing with my RST-135 (currently running RMS error of between 1" to 1.5"), when I use my FSQ-85's relatively short focal length of 432 mm.

Your Cat51 should be able to tolerate a 1" to 1.5" RMS error too, with its even shorter focal length.

Anyhow, if you are seeing a tracking error in the same range, it is on par with what you can achieve with the current ASIAIR software, and it is neither your error, nor the RST-135's.

If your tracking error is significantly larger than what I am seeing on my RST-135, then there is something else that is very wrong. Again, I cannot tell how much your errors are since I don't have your entire log file, but you should be able to run the PHD2 Log Viewer to see for yourself. But, first shorten the guide exposure time to 0.5 or 1 second, then recalibrate and carefully adjust the aggressiveness setting all over again.

For comparison, one RST-135 user using multi-star tracking with the real PHD2 is reporting 0.5" RMS tracking error with his RST-135 loaded with an 8" SCT. So, the RST-135 is capable of tracking well with heavy payloads; just not with ASIAIR v1.5.

Chen

cpatel823

Thank you Chen for the advice. I will make the suggested adjustments as suggested and try again when I have another clear night, maybe next week when we get a break in the clouds down in Livermore.

Thank you ZWO also for the suggestion of using PHD2 Log Viewer, makes things a lot easier.