Around the Clock Observations of the Q0957+561 A,B Gravitationally Lensed Quasar II: Results for the second observing season

Wesley N. Colley; Rudolph E. Schild; Cristina Abajas; David Alcalde; Zeki Aslan; Ilfan Bikmaev; Vahram Chavushyan; Luis Chinarro; Jean-Philippe Cournoyer; Richard Crowe; Vladimir Dudinov; Anna Kathinka; Dalland Evans; Young-Beom Jeon; Luis J. Goicoechea; Orhan Golbasi; Irek Khamitov; Kjetil Kjernsmo; Hyun Ju Lee; Jonghwan Lee; Ki Won Lee; Myung Gyoon Lee; Omar Lopez-Cruz; Evencio Mediavilla; Anthony F. J. Moffatt; Raul Mujica; Aurora M. Ullan; Alexander Oscoz; Myeong-Gu Park; Norman Purves; Nail Sakhibullin; Igor Sinelnikov; Rolf Stabell; Alan Stockton; Jan Teuber; Roy Thompson; Hwa-Sung Woo; Alexander Zheleznyak

doi:10.1086/368076

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Around the Clock Observations of the Q0957+561 A,B Gravitationally Lensed Quasar II: Results for the second observing season

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Abstract

We report on an observing campaign in March 2001 to monitor the brightness of the later arriving Q0957+561 B image in order to compare with the previously published brightness observations of the (first arriving) A image. The 12 participating observatories provided 3543 image frames which we have analyzed for brightness fluctuations. From our classical methods for time delay determination, we find a 417.09 +/- 0.07 day time delay which should be free of effects due to incomplete sampling. During the campaign period, the quasar brightness was relatively constant and only small fluctuations were found; we compare the structure function for the new data with structure function estimates for the 1995--6 epoch, and show that the structure function is statistically non-stationary. We also examine the data for any evidence of correlated fluctuations at zero lag. We discuss the limits to our ability to measure the cosmological time delay if the quasar's emitting surface is time resolved, as seems likely.

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Wesley N. Colley, Rudolph E. Schild, Cristina Abajas, David Alcalde, Zeki Aslan, Ilfan Bikmaev, Vahram Chavushyan, Luis Chinarro, Jean-Philippe Cournoyer, Richard Crowe, Vladimir Dudinov, Anna Kathinka, Dalland Evans, Young-Beom Jeon, Luis J. Goicoechea, Orhan Golbasi, Irek Khamitov, Kjetil Kjernsmo, Hyun Ju Lee, Jonghwan Lee, Ki Won Lee, Myung Gyoon Lee, Omar Lopez-Cruz, Evencio Mediavilla, Anthony F. J. Moffatt, Raul Mujica, Aurora M. Ullan, Alexander Oscoz, Myeong-Gu Park, Norman Purves, Nail Sakhibullin, Igor Sinelnikov, Rolf Stabell, Alan Stockton, Jan Teuber, Roy Thompson, Hwa-Sung Woo, Alexander Zheleznyak. 2002-10-17. Around the Clock Observations of the Q0957+561 A,B Gravitationally Lensed Quasar II: Results for the second observing season. https://doi.org/10.1086/368076

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