Identifying Vedic Asterisms - Software?

In om, Gautam
Majumdar wrote:

| As for the specific example of Shatapatha Brahmana, D P Chattopadhyaya
| in his book Science & Technology in Ancient India, suggested that some
| of the observational findings included were traditional,

One particular passage in the SB is noteworthy for the discussion it has
generated. See

http://www1.shore.net/~india/ejvs/ejvs0502/ejvs0502.txt

The figures are accessible from the TOC listing at

http://www1.shore.net/~india/ejvs/issues.html

It's interesting stuff, except that one basic point of astronomy leaves
me quite confused: either I'm misunderstanding the astronomy, or the
discussion in the paper above seems offbase.

Azimuth 90 degrees points to true East. Should asterisms located on the
celestial equator rise at that point on any night that they are visible?
Related: except for an imperceptible-to-the-naked-eye difference due to
parallax as the earth goes around the sun, isn't this true throughout
the year? (Until the long term effect of precession relocates the
celestial equator perceptibly, of course.)

If this is so, then the verb 'cyavante' (literally, 'moves' or 'is
unstable/deflected') is being misinterpreted, as none of the asterisms
"move" in any real sense. They merely rise at different points on the
eatern horizon regardless of the season, so a verb connoting variability
seems quite misplaced.

What have I misunderstood?

In article ,
Arjun Ray writes:
Azimuth 90 degrees points to true East. Should asterisms located on the
celestial equator rise at that point on any night that they are visible?

Yes, if you ignore atmospheric refraction and other small effects and
if your altitude is not very far from sea level. For naked eye
astronomy at non-polar latitudes, and in particular from Delhi, the
approximation should be excellent.

Related: except for an imperceptible-to-the-naked-eye difference due to
parallax as the earth goes around the sun, isn't this true throughout
the year? (Until the long term effect of precession relocates the
celestial equator perceptibly, of course.)

Parallax is a tiny effect, at most an arcsecond. Very hard to
measure, even with modern telescopes.

If this is so, then the verb 'cyavante' (literally, 'moves' or 'is
unstable/deflected') is being misinterpreted, as none of the asterisms
"move" in any real sense. They merely rise at different points on the
eatern horizon regardless of the season, so a verb connoting variability
seems quite misplaced.

Every star rises at a fixed point on the horizon, regardless of the
season. (Neglecting variation of atmospheric refraction with
temperature , i.e., season and other tiny effects and of course
neglecting precession, which changes the rise point over long time
scales.)

Could "move" refer to the change in elevation as an object rises?
If, as you imply, the meaning is "Different stars rise at different
places on the horizon," a verb denoting change is indeed misused. We
have a common example in English, though, where "vary" is often
(mis-)used to describe different objects having different properties
rather than in the sense of "change."

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
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In , (Steve
Willner) wrote:
| In article ,
| Arjun Ray writes:

| [The asterisms] merely rise at different points on the eastern
| horizon regardless of the season, so a verb connoting variability
| seems quite misplaced.

| Could "move" refer to the change in elevation as an object rises?

Unlikely. The context is clearly about the "eastern direction" as an
auspicious one.

| If, as you imply, the meaning is "Different stars rise at different
| places on the horizon," a verb denoting change is indeed misused. We
| have a common example in English, though, where "vary" is often
| (mis-)used to describe different objects having different properties
| rather than in the sense of "change."

Yes, as in "deviate". This is the meaning now being ascribed to the
verbal form found in the text, though a highly respected translation
runs as follows:

: etA ha vai prAcyai dizo na cyavante / sarvANi ha vA anyAni nakSatrANi
: prAchyai dizo cyavante / tat prAcyam evAsyaitad dizy Ahitau bhavataH /
: tasmAt kRttikAsv AdadhIta // (II. 1. 2.3)

: "And again they do not move away from the eastern quarter, whilst the
: other asterisms do move from the eastern quarter. Thus his (two fires)
: are established in the eastern quarter: for this reason he may set up
: his fires under the kRttikAs. (tr. Eggeling)

("prAcyai" is "East" or "forward" in the genitive or ablative case,
"dizo" - pronounced "disho" - is "direction", "na" is negation, and the
verb "cyavante" is present tense third person plural in the middle or
reflexive voice.) Dictionaries regularly define the verbal root "cyu"
to mean: stir, waver, fall, move. "Deviate" isn't that much of a
stretch, but it's a stretch nonetheless.

But even granting that, the context does not make clear whether kRttika
(the Pleiades) "not deviating from the eatern direction" is actually a
fact or just a dogmatic assertion - as, for example, could arise from a
prior, much older tradition, of *defining* "true east" as the point at
which the Pleiades rise!

The problem is that the text in question (the Shatapatha Brahmana) shows
knowledge of iron, which places it this side of 1000 BCE, whereas the
Pleiades lying on the celestial equator hasn't been true since some time
in the late third or early second millennium BCE: a difference in dating
of at least 1500 years.