Some portion of the upper side of the wing is visible and from that, we can see that it is the female of the Great Eggfly. I think there was one male also with those brighter markings on its upper wing but it did not sit and ask me to photograph. It flew away. Thanks JRB. I just recalled that I had got that id-ed on DG and even posted both male and female butterflies which came to my yard, sometime ago. I link here the female - I have a collage in that group showing both M & F:
