Advanced Guiding

PHD2 has settings that most people never change: the guide algorithm, the minimum move, the calibration step, the pulse limits, the exposure range and where it looks for a star. The Advanced guiding screen shows each one beside the value ARIS works out for your rig, and lets you hand any of them to ARIS.

Open the guider settings screen and tap the ADVANCED GUIDING card (“Algorithms · pulse limits · star search”). The card shows where things stand: Everything auto, N set by hand, N not applied, or N better values waiting. It appears on rigs where ARIS can write PHD2’s profile.

The rows and their auto values

The COMPUTED FROM line shows the numbers every auto value comes from: the guide focal length, the guide camera’s pixel size, its binning, the image scale and the mount’s guide rate. Guide optics setup opens the page where you set them. Until they are set, a row that needs them says “Set up the guide optics first — ARIS cannot work this out yet.”

Row	Auto value	Lane
Guide algorithm	RA: Predictive PEC on a strain-wave mount (ZWO AM3, AM5, AM5N, AM7; iOptron HAE, HAZ; Sky-Watcher Wave), Hysteresis on any other. Dec: Hysteresis.	RESTART
Minimum move	0.1515 + 0.1548 ÷ the image scale, and never under 0.15 px	LIVE
Calibration	The step that covers PHD2’s calibration distance in 12 pulses, rounded up to 50 ms	RESTART
Max pulse	The pulse that moves the star 2 px, between 50 and 2500 ms	RESTART
Auto exposure	500–2000 ms, target SNR 6	RESTART
AutoFind region	The central 70% of the frame. If no star is found there, ARIS searches the whole frame.	ACQUIRE

Each row has a line under it that says why the value is what it is. Its lane pill says when a change takes effect: LIVE now, ACQUIRE at the next star acquisition, RESTART after Apply now.

Never applied

Opening this screen changes nothing. A row on auto that has never been applied is only shown: ARIS does not write it to PHD2. Your rig guides as it did before until you save a row, tap Reset all to auto, or apply a better value.

How to read a row:

The value box shows the value in force now. A dashed box means that value is the auto; a solid box means it is not. If ARIS cannot read PHD2’s value, the box says unknown.
PHD2 (grey) means PHD2’s own value is in force: the row is not handed to ARIS yet, or its new value is queued and not in PHD2 yet.
manual (amber) means you set the value by hand.
not applied (grey) appears on AutoFind region, which is an ARIS setting with no PHD2 copy. Until you apply it, ARIS searches the Whole frame, as before.
On a row ARIS does not manage yet, the auto is offered under the box as auto and its value.

Change a row

Tap the row. The editor says whether the value is ARIS behaviour or part of the PHD2 profile.
Type a value, or leave the field empty to stay on auto. A line under the field says what Save will change.
Tap Save. Reset to auto gives the row back to ARIS.

Reset all to auto hands every row to ARIS at once. It first lists each change, from the current value to the auto, and then asks you to confirm with Reset all. PHD2 keeps your calibration.

Apply now

Minimum move takes effect at once, and AutoFind region at the next star acquisition. The other rows are part of PHD2’s profile and wait in a queue: a queued row reads “queued”, its value, and “not in PHD2 until Apply”.

When changes are queued, the screen says how many are not in PHD2 yet. Apply now restarts PHD2 to load them. This takes about 20 seconds, and PHD2 keeps your calibration. It counts the seconds, then shows Applied. or Not applied.

Apply now is refused while a sequence runs (a paused sequence counts as running), while PHD2 or the camera is busy, while guiding is on, or when the profile cannot be read.

Starting guiding from the Guider screen also applies queued values. A sequence’s own guide start does not.

Better values

A calibration also records how the mount’s guide pulses behave. If the pulses end when PHD2 takes the next frame, the rig lowers the Calibration auto to fit. When a calibration moves an auto on a row that is on auto, and PHD2 holds a different value, the rig notes it and sends one alert. The screen then shows a band such as 1 better guide setting waiting with APPLY, until the value reaches PHD2.

Guide exposure and gain per filter

ARIS can keep one guide exposure and one guide gain for each filter. This helps when the guide sensor looks through the filters, as with an off-axis guider or a camera with a built-in guide sensor.

On the Filter Wheel screen, each filter row shows GUIDE EXP and GUIDE GAIN. Tap a filter to edit them:

Guide exposure is Rig default or one of PHD2’s steps: 0.2, 0.5, 1, 1.5, 2 or 3 s.
Guide gain is the camera’s own gain number, never a percentage. The range under it is the camera’s, for example 0–600 on an ASI220MM Mini. A value outside the range is refused.
An empty field uses the rig default. Clear empties both.

On the Guider screen, set the exposure and gain while you guide, then tap Save to and the filter name (or Update, when one is already saved). All filters › opens the list.

ARIS applies a filter’s saved exposure, then its gain, when the filter changes in a sequence, when you move the wheel by hand, and when the guider reconnects. A filter with nothing saved changes nothing. On a camera whose guide sensor sits behind the filters, the change happens inside the guiding pause for the filter move. A NINA rig applies the exposure only.

Recalibrate

The CALIBRATION section of the guider settings screen has Clear Calibration Data and Recalibrate. Recalibrate asks first, because it moves the mount, then shows its progress and ends with ”✓ Calibrated · guiding resumed” or with the reason it did not finish.

If Rotate to reference for AF / solve / backlash is on (see Filter Focus Offsets), the calibration runs through the reference filter and the wheel goes back afterwards. If you turn the wheel yourself in the meantime, or a sequence or another camera flow starts, the wheel stays put and ARIS says why.