Dhanuśarāgra (धनुशराग्र)

Authors: Shylaja, Susanne M Hoffmann, ASE Tech Team, IanRidpath

---

Dhanuśarāgra is in the red circle envelopes both the stars γ1 and γ2. The other circle is for μ Sgr. These two are marked on the image from Sidney Hall Urania, wikicommons

...

Etymology and History

Name Variants

• Dhanuśarāgra (धनुशराग्र)
• Dhanusharagra

Origin of Constellation

The term Dhanuśarāgra (धनुशराग्र) literally means tip of the arrow. Dhanu - bow, śara - arrow, agra - tip. It agrees with the position corresponding to the tip of the arrow. There are two stars γ1 and γ2, shown inside the red circle in the diagram. Although the original diagram responsible for the nomenclature is not traceable, the depiction here supports the etymology of the name .

This star name thus can be for γ1 Sagittarii. (W Sagittarii, HR 6742, HD 164975, SAO 186237, HIP 88567, ADS 11029, CCDM 18050-2935)

Transfer and Transformation

This name has been found in the catalogue of astrolabes translated from Persian. The name has been coined as shown in the two examples below.

The astrolabes were introduced in to Indian astronomy by sea farers from the Middle East. In the earliest manual prepared by Mahendra Suri in the 1370CE only 32 bright stars were listed. Subsequently other faint stars also were marked. Based on the original data, the stars names were literally translated in most of the cases. The name is listed in the manual by Mahendra Suri as the 26th star. It may be seen that there was no Persian name for Dhanuśarāgra . Therefore, this must have been coined to suit the imaginary picture.

The list from Mahendra Suri (1370CE) assigns number 26 for Dhanuśarāgra . It is not based on any original name.

In the astrolabe C006 (1644CE) made by Maniarama from Gujarat, India, the stars are marked with two letter abbreviations and the numeral corresponding to the list of Mahendra Suri. Dhanu 26 on the rete, therefore, will correspond to Dhanuśarāgra . The identification was done by stars overlay on the rete.

The close up view here shows the pointer on the rete. Using Spica (S) and Altair (A) as references, we see that the pointer is for a different star in Ophiucus. It is possible that the engraved number is in error.

Close up of the region in C006 showing numbers 26 Dhanu and 27.

Stars overlay on the rete of C006; reference stars are Altair (A) and Spica (S). The red circle is the pointer for Dhanuśarāgra - it appears to be for some star in Ophiucus.

C001 in the catalogue was prepared by Damodara of Ahmedabad, India, in 1605. The engraving on the dial reads Dhanuśirā ;this is μ Sgr. The catalogue reports Dhanuśarāgra as a correction. This is a curious case of mis-identification. The position on the rete matches with neither with Dhanuśira (μ Sgr) nor Dhanuśarāgra (γ Sgr). However, this brings out the important information that the star name Dhanuśarāgra was in use..

The position actually corresponds to the supernova of 1604 CE.

The region of Dhanuśarāgra in C001 with stars overlay shows the pointer to the location of the SN1604 with both μ Sgr and γ Sgr far from it.

This table shows that the star was misidentified as μ Sgr in the catalogue

The accuracy of the star dials cannot distinguish between the two stars γ1 and γ2. Therefore, Dhanuśarāgra is proposed for γ1 which now has no name ( W Sgr form the variable star catalogue).

References

• References (general)