Tantrasara (Krishnananda) 2.p31

2.p31

śivabījaṃ vahnisaṃsthaṃ vāmanetravibhūṣitam .
vindu nādātmakaṃ devi haṃsaḥ padamatho likhet .
anena manunā mantro bhāskarasya priyeṇa tu .
arghyaṃ dadyāditi śeṣaḥ .
viśeṣastu snānaprakaraṇe vaktavyaḥ .. 9 ..
tataḥ oṃ sūryamaṇḍalasthāyai amukadevatāyai namaḥ, ityanena
tadgāyatryā vā trivāraṃ jalaṃ nikṣipya tattaddevatāyā gāyatrīṃ
japet .. 10 ..

The seed-syllable of Śiva seated in fire, adorned with the left eye, / consisting of bindu and nāda, O goddess, and then one should write the word 'haṃsaḥ'. / With this mantra beloved of the Sun, the mantrin— / 'should offer arghya' is the ellipsis. / The particulars, however, are to be stated in the section on bathing. (9)
Then, with 'Oṃ, homage to the deity [named so-and-so] residing in the solar orb', or with its gāyatrī, having cast water three times, he should recite the gāyatrī of that deity. (10)