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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
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"

3332 results found.

  1. EP251221a: NOT optical upper limit
  2. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  3. EP251220a: NOT optical observations
  4. EP251221a: Einstein Probe detection of a fast X-ray transient
  5. EP251220a: EP-FXT follow-up observation
  6. EP 251220a: GOTO optical counterpart detection
  7. EP 251220a: COLIBRÍ detection of the optical counterpart
  8. EP251220a: Global MASTER-Net observations report
  9. EP251220a: EP detection of a fast X-ray transient
  10. EP251214b: KAIT optical upper limit
  11. EP251214a: Optical upper limit with Kinder observations
  12. EP251214b: Global MASTER-Net observations report
  13. EP251214b : Einstein Probe detection of a fast X-ray transient
  14. EP251214b : Einstein Probe detection of a fast X-ray transient
  15. EP251214b (EP trigger 01709250023): LCO optical limits
  16. EP251214a: KAIT optical upper limit
  17. EP251214a: EP-FXT non-detection and upper limit
  18. EP251214a: Global MASTER-Net observations report
  19. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  20. EP251212a: Global MASTER-Net observations report
  21. EP251212a: KAIT optical upper limit
  22. EP251212a: EP-FXT follow-up observation
  23. EP251212a: Einstein Probe detection of an X-ray transient
  24. EP251124a: Mondy optical upper limit
  25. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  26. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  27. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  28. The EP-WXT trigger 01709249380 is likely a flaring star
  29. Konus-Wind detection of GRB 251118A
  30. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  31. GRB 251202A: SVOM/GRM observation
  32. GRB 251203C: EP-FXT follow-up observation
  33. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  34. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  35. EP251130a: MAO/AZT-22 optical observations
  36. GRB 251202A / EP251202a: SVOM/VT optical observation
  37. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  38. GRB251129A/EP251129a: Swift UVOT detection
  39. GRB 251202A: Swift/UVOT Detection
  40. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  41. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  42. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  43. GRB 251202A: Swift-XRT afterglow detection
  44. EP251129a/GRB 251129A: NOWT Detection
  45. EP251130a: SVOM/VT optical observation
  46. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  47. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  48. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  49. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  50. EP251130a: Optical detections with Kinder observations
  51. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  52. EP251130A: Optical observation from 1.3m DFOT
  53. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  54. EP251130a: Swift-XRT counterpart detection
  55. EP251130a: Global MASTER-Net observations report
  56. EP251130a: COLIBRÍ optical counterpart candidate
  57. EP251130a: Einstein Probe detection of an X-ray transient
  58. EP251129a/GRB 251129A: EP-FXT follow-up observations
  59. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  60. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  61. GRB 251129A: Swift-XRT afterglow detection
  62. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  63. GRB 251129A / EP251129a: SVOM/VT optical fading
  64. EP251129a: Global MASTER-Net observations report
  65. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  66. EP251124a: Pan-STARRS ri-band imaging and photometry
  67. EP251124b follow-up observation by EP-FXT
  68. EP251124b: NOT r- and z-band optical upper limits
  69. EP251124b: Global MASTER-Net observations report
  70. EP251124b: EP-WXT detection of a fast X-ray transient
  71. EP251124a: Xinglong GWAC-F60A optical observation
  72. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  73. EP251124a: NOT r- and z-band optical upper limits
  74. EP251124a: Global MASTER-Net observations report
  75. EP251124a: Swift-XRT observations
  76. EP251124a: Optical upper limit with Kinder observations
  77. EP251118A: 6 GHz VLA Detection
  78. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  79. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  80. EP251124a: GROWTH-India Telescope optical upper limits
  81. EP251124a: Einstein Probe detection of an X-ray transient
  82. GRB 251122A/EP251122a: FTW optical and NIR observations
  83. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  84. The EP-WXT trigger 01709248783 is likely a flaring star
  85. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  86. GRB 251122A / EP251122a: EP-FXT counterpart detection
  87. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  88. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  89. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  90. GRB 251122A / EP251122a: LCO optical upper limits
  91. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  92. EP251122a: Global MASTER-Net observations report
  93. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  94. GRB 251122A / EP251122a: SVOM detection of a long burst
  95. EP251122a: Einstein Probe detection of an X-ray transient
  96. EP251118a: Continued Optical Detection with Kinder observations
  97. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  98. EP251118a: Xinglong-2.16m optical observation
  99. The EP-WXT trigger 01709248635 is likely a flaring star
  100. EP251118a: Optical detection with Kinder observations

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