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The criterion of Schoch

Several heliacal events are mentioned by Schoch (1924). The angle values for the inner and outer planets were derived by Schoch from some 70 observations (Schoch, 1924, page 732). Sirius angles are computed from Babylonian tables (Schoch, 1924, page 731). And the other star angles are recommended (Schoch, 1924, page 734). The angle γ that he tables is described as arcus visionis (depression of the Sun below the horizon): but is this description correct?

Object	Magn	Heliacal Event	Angle γ
Venus	-3.2	EL	5.2
Venus	-3.2	MF	5.7
Venus	-3.3	ML	5.8
Venus	-3.3	EF	5.8
Mercury	1.2	EL	11.1
Mercury	1.2	MF	13.2
Mercury	-0.5	ML	9.5
Mercury	-0.5	EF	10.5
Jupiter	-1.6	EL	7.4
Jupiter	-1.6	MF	9.3
Sirius	-1.5	EL	6.5
Sirius	-1.5	MF	9.3
Saturn	0.9	EL	10.5
Saturn	0.9	MF	13
Mars	1.8	EL	14.2
Mars	1.8	MF	15.5
Star (\|DAzi\|<25)	-3	EL	5.8
Star (\|DAzi\|<25)	-2	MF	6.5
Star (\|DAzi\|<25)	-2	EL	7
Star (\|DAzi\|<25)	-2	MF	8
Star (\|DAzi\|<25)	-1	EL	8.5
Star (\|DAzi\|<25)	-1	MF	9.5
Star (\|DAzi\|<25)	0	EL	9.5
Star (\|DAzi\|<25)	0	MF	10.5
Star (\|DAzi\|<25)	1	EL	10.5
Star (\|DAzi\|<25)	1	MF	11.5
Star (\|DAzi\|<25)	2	EL	12.5
Star (\|DAzi\|<25)	2	MF	13.5
Star (\|DAzi\|<25)	3	EL	15
Star (\|DAzi\|<25)	3	MF	16

The different heliacal (MF&ML&EF&EL) events are explained on this webpage.

Some evaluation points

The description of the angle γ that Schoch uses in his tables (Schoch, 1924, page 734) is: 'The arcus visionis of a planet or of Sirius is the depression of the Sun below the horizon, measured in the vertical circle for the moment when the star sets on the last evening when it is visible or rises on the first morning when it is visible'. So one would expect it to be the Arcus Visionis as defined by Ptolemy.

But is his angle 'arcus visionis' indeed the Arcus Visionis or does Schoch use the AV?
Comparing the angle γ of Schoch (Schoch, 1924, page 734) with Kolev's observations one gets the below graph:

It looks that Schoch's angle γ is closer to the AV than to the Arcus Visionis (-AltSun)!
Schoch's AV looks to be for low values of AEC, as he refers in his text to: 'For places with a very clear sky (such as Babylon and Athens)' (Schoch, 1924, page 734).
That Schoch uses the AV instead of the Arcus Visionis can also be derived from the statement made about a 'very clear sky'. The Arcus Visionis is not really dependent on the AEC (aka atmospheric conditions), so that reference would not have been relevant.

References

Schoch, Carl. 1924. 'The 'Arcus Visionis' of the planets in the Babylonian observations', Monthly Notices of the Royal Astronomical Society, Vol 84: pp. 731-34.

Acknowledgements

I would like to thank people for their help and constructive feedback. Any remaining errors in methodology or results are my responsibility of course!!! If you want to provide constructive feedback, let me know.

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Major content related changes: April 2, 2017