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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').

19136 results found.

  1. EP250304a: REM NIR upper limits
  2. EP250302a: Mondy Continued Optical Observations
  3. EP250304a: TRT optical counterpart detection
  4. EP250304a: Global MASTER-Net observations report
  5. EP250302a: SVOM/VT optical observation
  6. EP250302a: SAO RAS optical observations
  7. EP250225a: the candidate optical counterpart is an AGN
  8. EP250302a: Kinder optical follow-up observations
  9. EP250302a: NUTTelA-TAO Early Measurments
  10. EP250302a: REM NIR upper limits
  11. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  12. EP250302a: Mondy Observations and Optical Light Curve
  13. EP250302a: VLT/MUSE optical redshift z = 1.131
  14. EP250302A: VLT near-infrared observations
  15. EP250302A: VLT/X-shooter tentative redshift
  16. EP250302a: OHP/T193 optical and spectroscopic observations
  17. EP250302a: Global MASTER-Net observations report
  18. EP250302a: Xinglong F60B optical observation
  19. EP250302a: Swift-XRT observations of a fading X-ray source
  20. EP250302a: Einstein Probe detection of an X-ray transient
  21. EP250302a: SVOM/C-GFT optical observations
  22. GRB 250226A: GRANDMA Optical Observations
  23. EP250302a: Montarrenti Observatory optical detection
  24. Fermi GRB 250302A: Global MASTER-Net observations report
  25. EP250302a: FTW optical and NIR detection
  26. EP250302a: Nanshan/HMT optical counterpart detection
  27. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  28. GRB 250225B: VLT near-infrared afterglow confirmation
  29. EP250228a: Optical observations with Kinder and Swift/UVOT
  30. GRB 250226A: KAO Optical Upper Limit
  31. GRB 250226A: AbAO AS-32 Optical Upper Limit
  32. EP250227a: Global MASTER-Net observations report
  33. EP250223A: Upper limits from Fermi-GBM Observations
  34. EP250227a: TRT optical upper limit
  35. GRB 250225B: VLT/HAWKI near-infrared observations
  36. EP250227a: Optical upper limits with Kinder observations
  37. EP250227a: NOT optical observations
  38. EP250228a: updates on the EP observations
  39. EP250223a: J band upper limit by SYSU 80cm telescope
  40. EP250228a: Global MASTER-Net observations report
  41. GRB 250226A / EP250226a: LCO detection of the afterglow
  42. GRB 250225B: VLT/Xshooter imaging
  43. GRB 250205A / EP250205A: further radio observations with the VLA
  44. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  45. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  46. GRB 250225B: INTEGRAL SPI-ACS detection
  47. EP250225a: NOT optical candidate counterpart
  48. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  49. EP250226a / GRB 250226A: SVOM/VT optical observations
  50. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  51. EP250225a: TRT optical upper limits
  52. EP250226a/GRB 250226A: 1.6m Mephisto observations
  53. LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
  54. EP250226a/GRB 250226A: Kinder optical follow-up observations
  55. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  56. Fermi GRB 250226B: Global MASTER-Net observations report
  57. GRB 250221A: ATCA Detections and Upper Limits
  58. GRB 250225B: REM NIR upper limits
  59. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  60. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  61. GRB 250225B: VLT optical and near-infrared candidate counterpart
  62. GRB 250225B: VLT/FORS2 candidate optical afterglow
  63. GRB 250221A: EP-FXT detection of the X-ray afterglow
  64. EP250226a/GRB 250226A: GSP detects optical counterpart
  65. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  66. EP250226a: Global MASTER-Net observations report
  67. Swift GRB 250225B: Global MASTER-Net observations report
  68. Fermi GRB 250226A: Global MASTER-Net observations report
  69. Fermi trigger No 762205158: Global MASTER-Net observations report
  70. EP250225a: Global MASTER-Net observations report
  71. EP250225a: GSP optical upper limit
  72. EP250225a: Einstein Probe detected of a fast X-ray transient
  73. Fermi GRB 250225A: Global MASTER-Net observations report
  74. GRB 250225B: Swift detection of a burst
  75. EP250223a: GROWTH-India Telescope optical observations
  76. EP250215A: J band upper limit by SYSU 80cm telescope
  77. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  78. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  79. EP250223a: Kinder optical follow-up observations
  80. GRB 250207a: ATCA Radio Upper Limits
  81. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  82. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  83. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  84. EP250223a: GOTO optical afterglow detections
  85. EP250223a: REM NIR upper limit
  86. EP250223a: TRT optical afterglow observation
  87. EP250223a: refined analysis of the EP-WXT and FXT observations
  88. EP250223a: 1.6m Mephisto and 50cm array observations
  89. EP250223a: SVOM/VT optical observation
  90. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  91. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
  92. EP250223a: OASDG optical observations
  93. EP250223a: LCO detection of the afterglow
  94. EP250223a: NOT redshift z = 2.756
  95. EP250223a: NOT optical afterglow candidate
  96. EP250223a: Global MASTER-Net observations report
  97. GRB 250221A: VLA radio detection
  98. Fermi GRB 250223A: Global MASTER-Net observations report
  99. Fermi trigger No 762020305: Global MASTER-Net observations report
  100. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation

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