I wrote the first paragraph below before I wrote my commentary about Jetstar in today's image 0197. Ah, what the heck, it bears repeating.
Jetstar is a subsidiary of Qantas. It is the low-cost, cheap and nasty (yes, it is possible to be even nastier than Qantas) sub brand for people who don't have a lot of money to fly, and don't mind if their flights are delayed by about 2 weeks, and their luggage by about 4. That may be hyperbole, but I doubt it's by much. Unless it was a life or death emergency, there is no way that I would fly Jetstar.
Despite this distinction, it's odd that Qantas and Jetstar should be departing from the same airport at around the same time. Only a couple of minutes ago I shot some images of a Boeing 737 flying as QF 44 from Bali, and here we have Jetstar 787-8 VH-VKB (delivered December 2013) arriving as JST38, also from Denpasar Bali.
According to Flightaware, JST38 was due in at 07:20. If so it was clearly running early. Or, given that it's Jetstar, it's possible that it was just yesterday's flight running late.
Interestingly, JST38 was already in my keywords list meaning that I must have shot an aircraft flying that route previously. However clearly it wasn't VH-VKB, which was not in my keywords list.
(Found it; image "150131_063436_3310 At Cross Purposes" from 31 January 2015 and which (at the time of writing) was in my main Sydney Aviation gallery. The flight that day was still a 787-8, but it was VH-VHD.)