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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').

18787 results found.

  1. Konus-Wind detection of GRB 250306A
  2. GRB 250306A: NuSTAR detection of the prompt emission
  3. EP250304a: MeerKAT detection of a possible radio counterpart
  4. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  5. EP250302a:Xinglong optical observations
  6. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  7. GRB250101A: Radio upper limits from VLA observations
  8. GRB 250305A: SVOM/GRM observation of a burst
  9. GRB 250305A: Fermi GBM Final Real-time Localization
  10. EP250302a: Optical Observations at CrAO and SAO RAS
  11. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  12. EP 250304A: Optical counterpart detection by LCO
  13. EP250302A: 1.3m DFOT optical afterglow detection
  14. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  15. Konus-Wind detection of GRB 250222A
  16. EP250304a: REM NIR upper limits
  17. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  18. EP250302a: Mondy Continued Optical Observations
  19. EP250304a: TRT optical counterpart detection
  20. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  21. EP250304a: Einstein Probe detection of an X-ray transient
  22. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  23. EP250302a: SAO RAS optical observations
  24. EP250302a : GIT optical follow-up
  25. EP250302a: Kinder optical follow-up observations
  26. EP250302a: Swift/UVOT detection
  27. EP250302a: optical observation from the INAF Asiago Observatory
  28. EP250302a: REM NIR upper limits
  29. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  30. EP250302a: Mondy Observations and Optical Light Curve
  31. EP250302a: VLT/MUSE optical redshift z = 1.131
  32. EP250302A: VLT near-infrared observations
  33. EP250302A: VLT/X-shooter tentative redshift
  34. EP250302a: OHP/T193 optical and spectroscopic observations
  35. EP250302a: Einstein Probe detection of an X-ray transient
  36. EP250302a: SVOM/C-GFT optical observations
  37. GRB 250226A: GRANDMA Optical Observations
  38. EP250302a: Montarrenti Observatory optical detection
  39. EP250302a: Nanshan/HMT optical counterpart detection
  40. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  41. GRB 250225B: VLT near-infrared afterglow confirmation
  42. EP250228a: Optical observations with Kinder and Swift/UVOT
  43. Konus-Wind detection of GRB 250226A
  44. GRB 250226A: KAO Optical Upper Limit
  45. GRB 250226A: AbAO AS-32 Optical Upper Limit
  46. EP250227a: TRT optical upper limit
  47. GRB 250225B: VLT/HAWKI near-infrared observations
  48. EP250227a: Optical upper limits with Kinder observations
  49. EP250227a: NOT optical observations
  50. EP250227a: Einstein Probe detected of a fast X-ray transient
  51. EP250228a: updates on the EP observations
  52. EP250223a: J band upper limit by SYSU 80cm telescope
  53. EP250228a: Einstein Probe detection of an X-ray transient
  54. GRB 250225B: VLT/Xshooter imaging
  55. GRB 250205A / EP250205A: further radio observations with the VLA
  56. EP250225a: NOT optical candidate counterpart
  57. EP250226a/GRB 250226A:Xinglong optical follow-up observations
  58. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  59. EP250225a: TRT optical upper limits
  60. EP250226a/GRB 250226A: 1.6m Mephisto observations
  61. EP250226a/GRB 250226A: Kinder optical follow-up observations
  62. LIGO/Virgo/KAGRA S250227e: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
  64. GRB 250225B: REM NIR upper limits
  65. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  66. Konus-Wind detection of GRB 250225B
  67. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  68. EP250223a: CrAO ZTSH optical observation
  69. GRB 250225B: VLT optical and near-infrared candidate counterpart
  70. GRB 250225B: VLT/FORS2 candidate optical afterglow
  71. GRB 250225B: SVOM/GRM observation of a long burst
  72. GRB 250226A: GECAM-B detection
  73. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  74. EP250226a / GRB 250226A: TRT optical counterpart observation
  75. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  76. EP250223a: GMG Optical Observation
  77. EP250225a: Einstein Probe detected of a fast X-ray transient
  78. EP250223a: GROWTH-India Telescope optical observations
  79. EP250215A: J band upper limit by SYSU 80cm telescope
  80. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  81. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  82. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  83. EP250223a: Kinder optical follow-up observations
  84. GRB 250119B: VZLUSAT-2 detection
  85. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  86. GRB 250202B: VZLUSAT-2 detection
  87. GRB 250222A: SVOM/GRM observation of a burst
  88. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  89. GRB 250210A: VZLUSAT-2 detection
  90. GRB 250206A: VZLUSAT-2 detection
  91. EP250223a: REM NIR upper limit
  92. EP250223a: TRT optical afterglow observation
  93. EP250223a: refined analysis of the EP-WXT and FXT observations
  94. EP250223a: 1.6m Mephisto and 50cm array observations
  95. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  96. 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
  97. EP250223a: OASDG optical observations
  98. EP250223a: NOT optical afterglow candidate
  99. EP250223a: Einstein Probe detection of an X-ray transient
  100. GRB 250221A: Optical counterpart detection by LCO.

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