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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.

"N/A_MC151116_R1" does not adhere to advanced search syntax. Please refer to the documentation and try again.
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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

10919 results found.

  1. LIGO/Virgo/KAGRA S251112cm: Swift XRT observations, 20 X-ray sources
  2. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  3. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  4. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  5. GRB 251112B: MAXI/GSC detection
  6. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  7. GRB 251111A: SVOM/VT optical observations with X-band data
  8. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  9. GRB 251106A: Swift/BAT arcminute localization of a burst
  10. GRB 251106A: MASTER optical observations
  11. GRB 251104A: SVOM detection of a burst
  12. GRB 251103B: MITSuME Akeno optical upper limits
  13. GRB 250926B: VZLUSAT-2 detection
  14. GRB 250926A: VZLUSAT-2 detection
  15. GRB 250925A: VZLUSAT-2 detection
  16. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  17. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  18. GRB251026B: PRIME H-band upper limit
  19. GRB 251028A: MAXI/GSC detection
  20. GRB 251022A: SVOM/GRM observation
  21. GRB 251017A: Mondy AZT-33IK and Koshka Zeiss-1000 optical observations
  22. GRB 251023B / EP251023b: Mondy optical upper limit
  23. GRB 251017A: INASAN-Kislovodsk optical observations
  24. GRB 251026A: Mondy optical upper limit
  25. GRB 251025B: Mondy optical observations
  26. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  27. EP251023a: Mondy optical observations
  28. GRB 251025C: CALET Gamma-Ray Burst Monitor detection
  29. GRB 251025B: MASTER OT detection
  30. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  31. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  32. GRB 251023C: CALET Gamma-Ray Burst Monitor detection
  33. GRB 251022A: Fermi GBM Observation
  34. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  35. GRB 251013C: ISON-Castelgrande observatory optical observations
  36. GRB 251022A: MASTER OT detection
  37. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  38. EP251023a: Einstein Probe detection of an X-ray transient
  39. GRB 251022A: Fermi-LAT detection
  40. GRB 250911A: MAXI/GSC detection
  41. GRB 251017A : RAPAS follow-up observations
  42. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  43. GRB 251018A: MASTER OT detection
  44. GRB 251017A: SVOM/VT optical observation
  45. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  46. Swift Trigger 1404295 is not a GRB
  47. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  49. GRB 251014D: Swift-BAT refined analysis
  50. GRB 251013C: VLA detection
  51. GRB 251014B: PRIME J-band upper limit
  52. GRB 251013C: SVOM/ECLAIRs refined analysis
  53. Swift Trigger 1404295: possible GRB 251015A
  54. GRB 251014B: Swift/UVOT Upper Limits
  55. GRB 251014D: Swift/UVOT Upper Limits
  56. GRB 251011B: SVOM/VT optical upper limit
  57. GRB 251014D: Swift detection of a burst
  58. GRB 251014A: PRIME near-infrared upper limits
  59. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  60. GRB 251013C: Fermi GBM Observation
  61. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  62. GRB 251013A: CALET Gamma-Ray Burst Monitor detection
  63. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  64. GRB 251013C: ALMA detection
  65. GRB 251013C: SAO RAS optical observations
  66. GRB 251013C: SVOM detection of a burst
  67. GRB 251003A: Mondy optical upper limit
  68. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation
  69. GRB 251011B inspection: MASTER orphan GRB detection
  70. GRB 251011B : MASTER optical observations
  71. GRB 251011B: Swift detection of a burst
  72. GRB 251006A: CALET Gamma-Ray Burst Monitor detection
  73. GRB 251007B - SVOM/ECLAIRs refined analysis
  74. GRB 251002A - SVOM/ECLAIRs refined analysis
  75. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  76. GRB 251007B: SVOM/VT optical candidate
  77. GRB 251007A: CALET Gamma-Ray Burst Monitor detection
  78. GRB 251005C: PRIME J-band upper limit
  79. GRB 251007B: SVOM/C-GFT upper limit
  80. GRB 251007B: SVOM detection of a faint burst
  81. GRB 251007B: Swift detection of a burst
  82. GRB 251007A: Swift detection of a burst with an optical counterpart
  83. GRB 251005C: SVOM/VT optical fading
  84. GRB 251005C: SVOM/VT optical candidate
  85. GRB 251005C: Swift/UVOT Upper Limits
  86. GRB 250902A: MSU cubesats detection
  87. GRB 251005C: Swift detection of a burst
  88. GRB 251002A: Mondy/AZT-33IK optical observations
  89. GRB 251001B: AbAO optical upper limit
  90. GRB 251002A: AbAO optical observations
  91. GRB 251001C: CALET Gamma-Ray Burst Monitor detection
  92. GRB 251002A: J band observations by SYSU 80cm infrared telescope
  93. GRB 251002A: OHP/T193 MISTRAL optical afterglow detection
  94. GRB 251002A: VLT/X-shooter spectroscopic redshift z = 2.178
  95. GRB 251002A: SVOM detection of a burst
  96. GRB 251001B: SVOM/VT optical observation
  97. GRB 250910A / EP250910a: VLT limits on the possible associated supernova
  98. LIGO/Virgo/KAGRA S250818k: further MeerKAT monitoring
  99. GRB 250910A / EP250910a: VLT/X-shooter host galaxy redshift z = 0.592
  100. GRB 250926A: CALET Gamma-Ray Burst Monitor detection

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